Important CS Programs

def greet(name):
    print("Hello,", name)
    print("Welcome to Class 12 Computer Science.")

greet("Riya")
greet("Aman")

def area_of_circle(r):
    return 3.14 * r * r

a = area_of_circle(7)
print("Area of circle:", a)

def min_max(L):
    return min(L), max(L)

small, big = min_max([45, 12, 89, 33, 7])
print("Smallest:", small)
print("Largest:", big)

def simple_interest(p, r=5, t=1):
    return p * r * t / 100

print(simple_interest(1000))           # r = 5 and t = 1 (default values)
print(simple_interest(1000, 8))        # t = 1 (default value)
print(simple_interest(t=2, p=5000))    # keyword arguments, in any order

def capitalize_words(words):
    result = []
    for w in words:
        result.append(w.capitalize())
    return result

print(capitalize_words(["python", "computer", "science"]))

def sum_positive(list1):
    total = 0
    for num in list1:
        if num > 0:
            total += num
    print(total)

sum_positive([10, -5, 20, -3, 7])    # 37

import random

def roll_dice():
    return random.randint(1, 6)    # 1 and 6 are both included

for i in range(5):
    print("Roll", i + 1, ":", roll_dice())

count = 0              # global variable

def show():
    count = 5          # local variable (a different 'count')
    print("Inside show():", count)

def increase():
    global count       # use the global 'count'
    count = count + 1

show()
increase()
increase()
print("Global count:", count)    # 2

def change(n, L):
    n = n + 10       # int is immutable: the caller's number does not change
    L.append(10)     # list is mutable: the caller's list changes

num = 5
marks = [1, 2, 3]
change(num, marks)
print("num   =", num)      # 5
print("marks =", marks)    # [1, 2, 3, 10]

def revNumber(num):
    rev = 0
    while num > 0:
        rem = num % 10
        rev = rev * 10 + rem
        num = num // 10
    return rev       # outside the loop

print(revNumber(1234))    # 4321

def CountVowels(s):
    c = 0
    for ch in s:                  # not range(s)
        if ch in 'aeiouAEIOU':    # is ch one of the vowels?
            c += 1                # += , not =+
    return c                      # return the count, not ch

print(CountVowels("Computer Science"))    # 6

def lenWords(STRING):
    T = ()
    for word in STRING.split():
        T = T + (len(word),)    # (x,) is a tuple with one item
    return T

print(lenWords("Come let us have some fun"))    # (4, 3, 2, 4, 4, 3)

def countNow(PLACES):
    for place in PLACES.values():
        if len(place) > 5:
            print(place.upper())

PLACES = {1: "Delhi", 2: "London", 3: "Paris", 4: "New York", 5: "Doha"}
countNow(PLACES)    # LONDON, NEW YORK

def showGrades(S):
    for name in S:
        marks = S[name]
        avg = sum(marks) / len(marks)
        if avg >= 90:
            grade = "A"
        elif avg >= 60:
            grade = "B"
        else:
            grade = "C"
        print(name, "-", grade)

S = {"AMIT": [92, 86, 64], "NAGMA": [65, 42, 43], "DAVID": [92, 90, 88]}
showGrades(S)

def Puzzle(W, N):
    result = ""
    for i in range(len(W)):
        if (i + 1) % N == 0:      # positions N, 2N, 3N ... (counting from 1)
            result += "_"
        else:
            result += W[i]
    return result

print(Puzzle("TELEVISION", 3))    # TE_EV_SI_N
print(Puzzle("TELEVISION", 4))    # TEL_VIS_ON

def cnt_even(pairs):
    c = 0
    for a, b in pairs:
        if a % 2 == 0 and b % 2 == 0:
            c += 1
    return c

pairs = ((2, 5), (4, 2), (9, 8), (12, 10))
print("Pairs with both numbers even:", cnt_even(pairs))    # 2

def remove_element(L, n):
    if n in L:
        L.remove(n)
    else:
        print("Element not found")

L = [10, 20, 30, 40]
remove_element(L, 30)
print(L)                  # [10, 20, 40]
remove_element(L, 99)     # Element not found

def swap_ends(T):
    if len(T) < 2:
        return T
    return (T[-1],) + T[1:-1] + (T[0],)

print(swap_ends((10, 20, 30, 40)))    # (40, 20, 30, 10)

def word_frequency(text):
    freq = {}
    for word in text.lower().split():
        freq[word] = freq.get(word, 0) + 1    # 0 when the word is new
    return freq

print(word_frequency("The cat and the dog and the bird"))
# {'the': 3, 'cat': 1, 'and': 2, 'dog': 1, 'bird': 1}

def is_armstrong(n):
    digits = str(n)
    power = len(digits)
    total = 0
    for d in digits:
        total += int(d) ** power
    return total == n          # True or False

def armstrong_in_range(a, b):
    result = []
    for n in range(a, b + 1):
        if is_armstrong(n):    # calling the other function
            result.append(n)
    return result

print(armstrong_in_range(100, 999))    # [153, 370, 371, 407]

def is_anagram(w1, w2):
    return sorted(w1.lower()) == sorted(w2.lower())

print(is_anagram("Listen", "Silent"))    # True
print(is_anagram("Python", "Typhon"))    # True
print(is_anagram("Hello", "World"))      # False

a = 10
b = 0
try:
    print(a / b)
except ZeroDivisionError:
    print("Error: cannot divide by zero.")
print("The program continues.")

try:
    age = int(input("Enter your age: "))
    print("Next year you will be", age + 1)
except ValueError:
    print("Please enter a whole number, e.g. 16.")

def divide_item(L, i, d):
    try:
        print("Result:", L[i] // d)
    except IndexError:
        print("Error: index", i, "is out of range.")
    except ZeroDivisionError:
        print("Error: cannot divide by zero.")
    except TypeError:
        print("Error: use numbers only.")

L = [10, 20, 30]
divide_item(L, 1, 5)      # Result: 4
divide_item(L, 7, 5)      # IndexError
divide_item(L, 1, 0)      # ZeroDivisionError
divide_item(L, 1, "2")    # TypeError

def safe_divide(a, b):
    try:
        result = a / b
    except ZeroDivisionError:
        print("Cannot divide by zero.")
    else:
        print("Answer:", result)    # only when there is no error
    finally:
        print("Done.")              # always

safe_divide(10, 4)
safe_divide(10, 0)

def set_marks(m):
    if m < 0 or m > 100:
        raise ValueError("Marks must be between 0 and 100")
    print("Marks saved:", m)

try:
    set_marks(85)
    set_marks(120)
except ValueError as e:
    print("Error:", e)

while True:
    try:
        n = int(input("Enter a number from 1 to 10: "))
        if 1 <= n <= 10:
            break                       # valid: leave the loop
        print("Out of range, try again.")
    except ValueError:
        print("That is not a number, try again.")

print("You entered", n)

def show_file(name):
    try:
        with open(name, "r") as f:
            print(f.read())
    except FileNotFoundError:
        print("Sorry,", name, "does not exist.")

with open("notes.txt", "w") as f:
    f.write("Exception handling stops a program from crashing.")

show_file("notes.txt")
show_file("missing.txt")

f = open("story.txt", "w")
f.write("Python is easy to learn.\n")
f.write("Files store data permanently.\n")
f.close()

f = open("story.txt", "r")
print(f.read())
f.close()

with open("diary.txt", "w") as f:
    f.write("Monday: Revised functions.\n")

with open("diary.txt", "a") as f:     # old data stays
    f.write("Tuesday: Solved file handling questions.\n")
    f.writelines(["Wednesday: Stack practice.\n", "Thursday: SQL joins.\n"])

with open("diary.txt", "r") as f:
    print(f.read())

with open("poem.txt", "w") as f:
    f.write("Twinkle twinkle\nLittle star\nHow I wonder\n")

f = open("poem.txt", "r")
print(f.read(7))         # first 7 characters: Twinkle
f.seek(0)                # back to the start
print(f.readline())      # one line (keeps the \n)
print(f.readlines())     # list of the remaining lines
f.close()

with open("story.txt", "w") as f:
    f.write("Python is fun.\nFiles keep data safe.\nPractice daily.\n")

lines = words = chars = 0
with open("story.txt", "r") as f:
    for line in f:
        lines += 1
        words += len(line.split())
        chars += len(line)

print("Lines:", lines)
print("Words:", words)
print("Characters:", chars)

with open("abc.txt", "w") as f:
    f.write("HELLO WORLD")

with open("abc.txt", "r") as f:
    print(f.read(5))      # HELLO
    print(f.tell())       # 5
    f.seek(0)             # to the beginning
    print(f.read(3))      # HEL
    f.seek(6)             # to position 6
    print(f.read())       # WORLD

with open("story.txt", "w") as f:
    f.write("Python is fun\nKeep practising daily\n")

with open("story.txt", "r") as f:
    for line in f:
        words = line.split()
        print("#".join(words))

with open("Poem.txt", "w") as f:
    f.write("Python Is Easy\nPractice Every Day!")

vowels = consonants = upper = lower = 0
with open("Poem.txt", "r") as f:
    text = f.read()
for ch in text:
    if ch.isalpha():
        if ch in "aeiouAEIOU":
            vowels += 1
        else:
            consonants += 1
        if ch.isupper():
            upper += 1
        else:
            lower += 1

print("Vowels:", vowels)
print("Consonants:", consonants)
print("Uppercase:", upper)
print("Lowercase:", lower)

def show_you_lines():
    f = open("Alpha.txt", "r")
    for line in f:
        words = line.split()
        if len(words) > 0 and words[0] == "You":    # skip empty lines
            print(line, end="")
    f.close()

with open("Alpha.txt", "w") as f:
    f.write("You are a good student.\nAlways be on time.\nYou can do it!\nYour book is here.\n")
show_you_lines()

def count_python():
    count = 0
    with open("Prog.txt", "r") as f:
        for word in f.read().split():
            if word.strip(".,!?").lower() == "python":    # ignore punctuation and case
                count += 1
    print("The word Python appears", count, "times.")

with open("Prog.txt", "w") as f:
    f.write("Python is popular. I like python!\nLearning Python is fun.")
count_python()    # 3

def show_vote_lines():
    with open("Elections.txt", "r") as f:
        for line in f:
            if "vote" in line:
                print(line, end="")

with open("Elections.txt", "w") as f:
    f.write("Every citizen should vote.\nElections are held every five years.\nYour vote is your voice.\n")
show_vote_lines()

def show_dot_lines():
    with open("Colors.txt", "r") as f:
        for line in f:
            if line.rstrip().endswith("."):    # rstrip() removes the \n
                print(line, end="")

with open("Colors.txt", "w") as f:
    f.write("Red is bright.\nBlue is calm\nGreen means go.\n")
show_dot_lines()

def no_vowel_start():
    with open("Story.txt", "r") as f:
        for line in f:
            if line[0] not in "aeiouAEIOU":
                print(line, end="")

with open("Story.txt", "w") as f:
    f.write("Once upon a time\nThere was a king\nAn honest man\nHe ruled well\n")
no_vowel_start()

def count_digits():
    with open("Space.txt", "r") as f:
        text = f.read()
    count = 0
    for ch in text:
        if ch.isdigit():
            count += 1
    return count

with open("Space.txt", "w") as f:
    f.write("Chandrayaan-3 landed in 2023.\nISRO launched 104 satellites in 2017.")
print("Digits:", count_digits())    # 12

def ee_words():
    with open("Space.txt", "r") as f:
        for word in f.read().split():
            if word.count("e") >= 2:
                print(word)

with open("Space.txt", "w") as f:
    f.write("The tree near the green fence\nSeven people need help")
ee_words()

def remove_a_lines():
    fin = open("source.txt", "r")
    lines = fin.readlines()
    fin.close()

    keep = open("source.txt", "w")      # lines without 'a' stay here
    moved = open("with_a.txt", "w")     # lines with 'a' go here
    for line in lines:
        if "a" in line:
            moved.write(line)
        else:
            keep.write(line)
    keep.close()
    moved.close()

with open("source.txt", "w") as f:
    f.write("Python is great\nIt is free\nCode every day\nJust do it\n")
remove_a_lines()
print("source.txt:\n" + open("source.txt").read())
print("with_a.txt:\n" + open("with_a.txt").read())

def vowel_words():
    vowels = "aeiouAEIOU"
    result = []
    with open("Report.txt", "r") as f:
        for word in f.read().split():
            if word[0] in vowels and word[-1] in vowels:
                result.append(word)
    print(" ".join(result))

with open("Report.txt", "w") as f:
    f.write("India is an ancient area\nUse one apple every time")
vowel_words()    # India area Use one apple

def year_lines():
    f = open("History.txt", "r")
    for line in f:
        for w in line.split():
            if w.isdigit() and len(w) == 4:
                print(line, end="")
                break               # print each line only once
    f.close()

with open("History.txt", "w") as f:
    f.write("India became independent in 1947\nThe Taj Mahal is in Agra\nThe Constitution began in 1950 and 26 January\n")
year_lines()

def max_vowel_line():
    best_line = ""
    best_count = -1
    with open("Novel.txt", "r") as f:
        for line in f:
            count = 0
            for ch in line:
                if ch in "aeiouAEIOU":
                    count += 1
            if count > best_count:
                best_count = count
                best_line = line
    print(best_line.rstrip(), "(", best_count, "vowels )")

with open("Novel.txt", "w") as f:
    f.write("The sky was dark\nAn eerie audio echoed outside\nWe ran home\n")
max_vowel_line()

def showInLines():
    with open("STORY.TXT", "r") as f:
        text = f.read()
    sentence = ""
    for ch in text:
        sentence += ch
        if ch in ".?!":
            print(sentence.strip())
            sentence = ""

with open("STORY.TXT", "w") as f:
    f.write("Our parents told us that we must eat vegetables to be healthy. "
            "And it turns out, our parents were right! So, what else did our parents tell?")
showInLines()

def replace_word(old, new):
    fin = open("source.txt", "r")
    fout = open("result.txt", "w")
    for line in fin:
        fout.write(line.replace(old, new))
    fin.close()
    fout.close()

with open("source.txt", "w") as f:
    f.write("I like Java.\nJava is useful.\n")
replace_word("Java", "Python")
print(open("result.txt").read())

def longest_word():
    longest = ""
    with open("story.txt", "r") as f:
        for word in f.read().split():
            if len(word) > len(longest):
                longest = word
    print("Longest word:", longest, "(", len(longest), "letters )")

with open("story.txt", "w") as f:
    f.write("Programming needs patience\nand regular practice")
longest_word()    # Programming

import pickle

marks = [85, 92, 78, 64]
f = open("marks.dat", "wb")      # wb = write binary
pickle.dump(marks, f)
f.close()

f = open("marks.dat", "rb")      # rb = read binary
data = pickle.load(f)
f.close()
print("Read from file:", data)

import pickle

students = [[1, "Riya", 88], [2, "Aman", 75], [3, "Sara", 93]]
with open("student.dat", "wb") as f:
    for rec in students:
        pickle.dump(rec, f)      # one record at a time

with open("student.dat", "rb") as f:
    try:
        while True:
            rec = pickle.load(f)
            print(rec)
    except EOFError:             # no more records
        pass

import pickle

with open("student.dat", "wb") as f:
    for rec in [[1, "Riya", 88], [2, "Aman", 75], [3, "Sara", 93]]:
        pickle.dump(rec, f)

def count_records():
    count = 0
    with open("student.dat", "rb") as f:
        try:
            while True:
                pickle.load(f)
                count += 1
        except EOFError:
            pass
    return count

print("Number of records:", count_records())

import pickle

def create():
    with open("roll.dat", "wb") as f:
        pickle.dump([1, "Riya"], f)
        pickle.dump([2, "Aman"], f)
        pickle.dump([3, "Sara"], f)

def search(roll):
    found = False
    with open("roll.dat", "rb") as f:
        try:
            while True:
                rec = pickle.load(f)
                if rec[0] == roll:
                    print("Name:", rec[1])
                    found = True
                    break
        except EOFError:
            pass
    if not found:
        print("Roll number", roll, "not found.")

create()
search(2)
search(7)

import pickle

def disp_Detail():
    f = open("EMP.DAT", "rb")
    try:
        while True:
            emp = pickle.load(f)
            if emp[2] < 25000:
                print(emp)
    except EOFError:
        pass
    f.close()

with open("EMP.DAT", "wb") as f:
    for rec in [[101, "Neha", 32000], [102, "Ravi", 21000], [103, "John", 18500]]:
        pickle.dump(rec, f)
disp_Detail()

import pickle

def Copy_new():
    fin = open("items.dat", "rb")
    fout = open("new_items.dat", "wb")
    try:
        while True:
            rec = pickle.load(fin)            # e.g. {1: ['Pen', 50]}
            for item_id in rec:
                if rec[item_id][1] > 1000:
                    pickle.dump(rec, fout)
    except EOFError:
        pass
    fin.close()
    fout.close()

with open("items.dat", "wb") as f:
    for rec in [{1: ["Pen", 50]}, {2: ["Printer", 8500]}, {3: ["Mouse", 1200]}]:
        pickle.dump(rec, f)
Copy_new()

with open("new_items.dat", "rb") as f:
    try:
        while True:
            print(pickle.load(f))
    except EOFError:
        pass

import pickle

def copyData():
    fin = open("SPORT.DAT", "rb")
    fout = open("BASKET.DAT", "wb")
    count = 0
    try:
        while True:
            rec = pickle.load(fin)
            if rec[0] == "Basket Ball":
                pickle.dump(rec, fout)
                count += 1
    except EOFError:
        pass
    fin.close()
    fout.close()
    return count

with open("SPORT.DAT", "wb") as f:
    for rec in [["Basket Ball", "Eagles", 5], ["Cricket", "Lions", 11], ["Basket Ball", "Hawks", 5]]:
        pickle.dump(rec, f)
print("Records copied:", copyData())    # 2

import pickle

def findType(mtype):
    f = open("CINEMA.DAT", "rb")
    try:
        while True:
            rec = pickle.load(f)              # e.g. {1: ['Lagaan', 'Sports']}
            for mno in rec:
                if rec[mno][1] == mtype:
                    print(mno, rec[mno][0], rec[mno][1])
    except EOFError:
        pass
    f.close()

with open("CINEMA.DAT", "wb") as f:
    for rec in [{1: ["Lagaan", "Sports"]}, {2: ["Taare Zameen Par", "Drama"]}, {3: ["Dangal", "Sports"]}]:
        pickle.dump(rec, f)
findType("Sports")

import pickle

def add_doctor(rec):
    with open("DOCTORS.DAT", "ab") as f:     # ab = append binary
        pickle.dump(rec, f)

def show_all():
    with open("DOCTORS.DAT", "rb") as f:
        try:
            while True:
                print(pickle.load(f))
        except EOFError:
            pass

open("DOCTORS.DAT", "wb").close()           # start with an empty file
add_doctor([1, "Dr. Mehta", "Cardiology", 12])
add_doctor([2, "Dr. Rao", "Neurology", 8])
show_all()

import pickle

with open("result.dat", "wb") as f:
    for rec in [[1, "Riya", 70], [2, "Aman", 65], [3, "Sara", 90]]:
        pickle.dump(rec, f)

def update_marks(roll, new_marks):
    records = []
    found = False
    with open("result.dat", "rb") as f:      # 1. read every record
        try:
            while True:
                rec = pickle.load(f)
                if rec[0] == roll:
                    rec[2] = new_marks           # 2. change the one we want
                    found = True
                records.append(rec)
        except EOFError:
            pass
    with open("result.dat", "wb") as f:      # 3. write them all back
        for rec in records:
            pickle.dump(rec, f)
    print("Updated." if found else "Roll number not found.")

roll = int(input("Roll number: "))
marks = int(input("New marks: "))
update_marks(roll, marks)

import pickle

def Append():
    rid = int(input("Resource ID: "))
    name = input("Name: ")
    expertise = input("Expertise: ")
    charges = int(input("Charges: "))
    with open("RESOURCES.DAT", "ab") as f:
        pickle.dump((rid, name, expertise, charges), f)

def Update():
    records = []
    with open("RESOURCES.DAT", "rb") as f:
        try:
            while True:
                r = pickle.load(f)
                # a tuple cannot be changed, so make a new one
                records.append((r[0], r[1], r[2], r[3] + 500))
        except EOFError:
            pass
    with open("RESOURCES.DAT", "wb") as f:
        for r in records:
            pickle.dump(r, f)

# Try it: two sample records (call Append() to type your own)
with open("RESOURCES.DAT", "wb") as f:
    pickle.dump((1, "Asha", "Python", 2000), f)
    pickle.dump((2, "Vikram", "SQL", 1500), f)
Update()
with open("RESOURCES.DAT", "rb") as f:
    try:
        while True:
            print(pickle.load(f))
    except EOFError:
        pass

import pickle

with open("student.dat", "wb") as f:
    for rec in [[1, "Riya", 88], [2, "Aman", 75], [3, "Sara", 93]]:
        pickle.dump(rec, f)

def delete_record(roll):
    keep = []
    with open("student.dat", "rb") as f:
        try:
            while True:
                rec = pickle.load(f)
                if rec[0] != roll:       # keep all the others
                    keep.append(rec)
        except EOFError:
            pass
    with open("student.dat", "wb") as f:
        for rec in keep:
            pickle.dump(rec, f)

delete_record(2)
with open("student.dat", "rb") as f:
    try:
        while True:
            print(pickle.load(f))
    except EOFError:
        pass

import csv

f = open("students.csv", "w", newline="")
w = csv.writer(f)
w.writerow(["Roll", "Name", "Marks"])    # header row
w.writerow([1, "Riya", 88])
w.writerow([2, "Aman", 75])
f.close()

print(open("students.csv").read())

import csv

rows = [["Roll", "Name", "Marks"],
        [1, "Riya", 88],
        [2, "Aman", 75],
        [3, "Sara", 93]]
with open("students.csv", "w", newline="") as f:
    csv.writer(f).writerows(rows)

print(open("students.csv").read())

import csv

with open("students.csv", "w", newline="") as f:
    csv.writer(f).writerows([["Roll", "Name", "Marks"], [1, "Riya", 88], [2, "Aman", 75]])

with open("students.csv", "r") as f:
    for row in csv.reader(f):
        print(row)

import csv

with open("students.csv", "w", newline="") as f:
    csv.writer(f).writerows([["Roll", "Name", "Marks"], [1, "Riya", 88], [2, "Aman", 75], [3, "Sara", 93]])

total = 0
with open("students.csv", "r") as f:
    r = csv.reader(f)
    next(r)                     # skip the header
    for row in r:
        total += int(row[2])    # values are read as strings
print("Total marks:", total)

import csv

def create():
    with open("users.csv", "w", newline="") as f:
        w = csv.writer(f)
        w.writerow(["riya01", "sun@123"])
        w.writerow(["aman02", "moon#45"])

def find_password(uid):
    with open("users.csv", "r") as f:
        for row in csv.reader(f):
            if row[0] == uid:
                print("Password:", row[1])
                return
    print("User-id not found.")

create()
find_password(input("Enter user-id: "))

import csv

def Add_Device():
    pid = int(input("Device ID: "))
    name = input("Device name: ")
    price = int(input("Price: "))
    with open("Peripheral.csv", "a", newline="") as f:
        csv.writer(f).writerow([pid, name, price])

def Count_Device():
    count = 0
    with open("Peripheral.csv", "r") as f:
        for row in csv.reader(f):
            if int(row[2]) < 1000:
                count += 1
    print("Devices priced below 1000:", count)

# Try it: sample records (call Add_Device() to type your own)
with open("Peripheral.csv", "w", newline="") as f:
    csv.writer(f).writerows([[1, "Mouse", 450], [2, "Printer", 9500], [3, "Keyboard", 800]])
Count_Device()    # 2

import csv

def Accept(sid, name, game, result):
    f = open("Result.csv", "a", newline="")
    w = csv.writer(f)
    if f.tell() == 0:                    # empty file: write the headings first
        w.writerow(["St_Id", "St_Name", "Game_Name", "Result"])
    w.writerow([sid, name, game, result])
    f.close()

def wonCount():
    count = 0
    with open("Result.csv", "r") as f:
        r = csv.reader(f)
        next(r)                          # skip the headings
        for row in r:
            if row[3] == "Won":
                count += 1
    print("Students who won:", count)

open("Result.csv", "w").close()          # start with an empty file
Accept(1, "Riya", "Chess", "Won")
Accept(2, "Aman", "Kabaddi", "Lost")
Accept(3, "Sara", "Badminton", "Won")
wonCount()    # 2

import csv

def NewMembers():
    n = int(input("How many members? "))
    with open("CLUB.CSV", "a", newline="") as f:
        w = csv.writer(f)
        for i in range(n):
            mno = int(input("Member no: "))
            name = input("Name: ")
            mobile = input("Mobile: ")
            fee = int(input("Fee: "))
            w.writerow([mno, name, mobile, fee])

def PriorityMember():
    with open("CLUB.CSV", "r") as f:
        for row in csv.reader(f):
            if int(row[3]) > 35000:
                print(row)

# Try it: sample records (call NewMembers() to type your own)
with open("CLUB.CSV", "w", newline="") as f:
    csv.writer(f).writerows([[1, "Kiran", "9800000001", 40000], [2, "Dev", "9800000002", 25000], [3, "Meera", "9800000003", 52000]])
PriorityMember()

import csv

def AddRental():
    vid = input("Vehicle ID: ")
    vtype = input("Vehicle type: ")
    hours = int(input("Hours rented: "))
    rate = int(input("Rate per hour: "))
    with open("Rentals.csv", "a", newline="") as f:
        csv.writer(f).writerow([vid, vtype, hours, rate])

def CalculateTotalRent():
    total = 0
    with open("Rentals.csv", "r") as f:
        for row in csv.reader(f):
            total += int(row[2]) * int(row[3])
    return total

# Try it: sample records (call AddRental() to type your own)
with open("Rentals.csv", "w", newline="") as f:
    csv.writer(f).writerows([["V1", "Car", 5, 300], ["V2", "Bike", 3, 100], ["V3", "Car", 2, 300]])
print("Total rent earned:", CalculateTotalRent())    # 2400

import csv

def copy_big_states():
    fin = open("States.csv", "r")
    fout = open("More.csv", "a", newline="")
    r = csv.reader(fin)
    w = csv.writer(fout)
    next(r)                               # skip the header row
    for row in r:
        if int(row[2]) > 10000000:
            w.writerow(row)
    fin.close()
    fout.close()

with open("States.csv", "w", newline="") as f:
    csv.writer(f).writerows([["State", "Capital", "Population", "Language"],
                             ["Kerala", "Thiruvananthapuram", 33406061, "Malayalam"],
                             ["Goa", "Panaji", 1458545, "Konkani"],
                             ["Punjab", "Chandigarh", 27743338, "Punjabi"]])
open("More.csv", "w").close()            # start with an empty file
copy_big_states()
print(open("More.csv").read())

import csv

with open("students.csv", "w", newline="") as f:
    csv.writer(f).writerows([["Roll", "Name", "Marks"], ["1", "Riya", "88"], ["2", "Aman", "75"]])

def update_marks(roll, new_marks):
    with open("students.csv", "r") as f:
        rows = list(csv.reader(f))         # all rows in a list
    for row in rows[1:]:                   # skip the header
        if row[0] == str(roll):
            row[2] = str(new_marks)
    with open("students.csv", "w", newline="") as f:
        csv.writer(f).writerows(rows)

update_marks(2, 81)
print(open("students.csv").read())

stack = []
stack.append(10)      # push
stack.append(20)
stack.append(30)
print("Stack:", stack)

print("Popped:", stack.pop())    # 30 (the last one in)
print("Popped:", stack.pop())    # 20
print("Stack now:", stack)

def isEmpty(stk):
    return len(stk) == 0

def peek(stk):
    if isEmpty(stk):
        return "Stack Empty"
    return stk[-1]                 # top item, not removed

def display(stk):
    for i in range(len(stk) - 1, -1, -1):    # top to bottom
        print(stk[i])

books = ["Maths", "Physics", "Chemistry"]
print("Top:", peek(books))
display(books)
print(isEmpty([]))                 # True

stack = []

def push(item):
    stack.append(item)

def pop():
    if len(stack) == 0:
        print("Underflow: stack is empty")
    else:
        print("Popped:", stack.pop())

def peek():
    if len(stack) == 0:
        print("Stack is empty")
    else:
        print("Top:", stack[-1])

def display():
    print("Stack (top first):", stack[::-1])

while True:
    print("1.Push 2.Pop 3.Peek 4.Display 5.Exit")
    ch = input("Enter choice: ")
    if ch == "1":
        push(int(input("Number: ")))
    elif ch == "2":
        pop()
    elif ch == "3":
        peek()
    elif ch == "4":
        display()
    elif ch == "5":
        break
    else:
        print("Invalid choice")

Nums = [213, 10025, 167, 254923, 14, 1297653, 31498, 386, 92765]
BigNums = []

def PushBig():
    for n in Nums:
        if len(str(n)) >= 5:
            BigNums.append(n)

def PopBig():
    while len(BigNums) > 0:
        print(BigNums.pop())
    print("Stack Empty")

PushBig()
print("Stack:", BigNums)
PopBig()

travel = []

def Push_element(NList):
    for L in NList:
        if L[1] != "India" and L[2] < 3500:
            travel.append([L[0], L[1]])

def Pop_element():
    while len(travel) > 0:
        print(travel.pop())
    print("Stack Empty")

NList = [["New York", "U.S.A.", 11734], ["Naypyidaw", "Myanmar", 3219],
         ["Dubai", "UAE", 2194], ["London", "England", 6693],
         ["Gangtok", "India", 1580], ["Columbo", "Sri Lanka", 3405]]
Push_element(NList)
Pop_element()

B = [("Machine Learning Basics", 550), ("World Geography", 450),
     ("Wonder World", 140), ("AI Revolution", 750)]
Books = []

def Push_element():
    for item in B:
        if item[1] > 250:
            Books.append(item)

def Pop_element():
    while Books:                  # True while the stack is not empty
        print(Books.pop())
    print("Stack Empty")

Push_element()
Pop_element()

stack = []

for i in range(10):
    n = int(input("Enter integer " + str(i + 1) + ": "))
    if 100 <= abs(n) <= 999 and n % 2 == 0:    # 3 digits and even
        stack.append(n)

while stack:
    print(stack.pop())
print("Stack Empty")

def reverse_string(s):
    stack = []
    for ch in s:
        stack.append(ch)        # push
    result = ""
    while stack:
        result += stack.pop()   # pop
    return result

word = "COMPUTER"
print(reverse_string(word))                       # RETUPMOC
print("Palindrome?", reverse_string("MADAM") == "MADAM")

def to_binary(n):
    if n == 0:
        return "0"
    stack = []
    while n > 0:
        stack.append(n % 2)      # push the remainder
        n = n // 2
    binary = ""
    while stack:
        binary += str(stack.pop())
    return binary

print(to_binary(13))    # 1101
print(to_binary(40))    # 101000

def is_balanced(expr):
    pairs = {")": "(", "]": "[", "}": "{"}
    stack = []
    for ch in expr:
        if ch in "([{":
            stack.append(ch)
        elif ch in ")]}":
            if not stack or stack.pop() != pairs[ch]:
                return False
    return len(stack) == 0

print(is_balanced("(a+b)*[c-d]"))    # True
print(is_balanced("{(a+b]}"))        # False
print(is_balanced("((a+b)"))         # False

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="tiger", database="school")
if con.is_connected():
    print("Connected to MySQL")
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="tiger", database="school")
cur = con.cursor()
cur.execute("CREATE TABLE IF NOT EXISTS student (rno INT PRIMARY KEY, name VARCHAR(20), marks INT)")
cur.execute("INSERT INTO student VALUES (1, 'Riya', 88)")
cur.execute("INSERT INTO student VALUES (2, 'Aman', 75)")
con.commit()                  # save the changes
print("Records inserted")
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="airplane", database="Travel")
cur = con.cursor()
cur.execute("SELECT * FROM flight")
data = cur.fetchall()          # list of tuples, one per row
for row in data:
    print(row)
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="admin",
                              password="root", database="SCHOOL")
cur = con.cursor()
cur.execute("SELECT * FROM Account WHERE fees < 5000")
for row in cur.fetchall():
    print(row)
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="tiger", database="SCHOOL")
cur = con.cursor()
rno = int(input("Roll number: "))
name = input("Name: ")
dob = input("Date of birth (YYYY-MM-DD): ")
fee = float(input("Fee: "))
query = "INSERT INTO Student VALUES ({}, '{}', '{}', {})".format(rno, name, dob, fee)
cur.execute(query)
con.commit()
print("Record added")
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="admin",
                              password="Shopping", database="Keeper")
cur = con.cursor()
cur.execute("UPDATE shop SET Qty = 20 WHERE Item_code = 111")
con.commit()
print(cur.rowcount, "record(s) updated")
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="librarian",
                              password="lib@2025", database="LibraryDB")
cur = con.cursor()
cur.execute("UPDATE book_records SET Book_Title = 'Data Structures in Python' WHERE Book_ID = 109")
con.commit()
print("Book title updated")
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="tiger", database="school")
cur = con.cursor()
cur.execute("SELECT name, marks FROM student WHERE marks >= 80")
row = cur.fetchone()
while row is not None:
    print(row[0], row[1])
    row = cur.fetchone()
print("Rows read:", cur.rowcount)
con.close()

import mysql.connector

con = mysql.connector.connect(host="localhost", user="root",
                              password="tiger", database="school")
cur = con.cursor()
rno = int(input("Roll number to delete: "))
cur.execute("DELETE FROM student WHERE rno = %s", (rno,))
con.commit()
if cur.rowcount == 0:
    print("No such roll number")
else:
    print("Record deleted")
con.close()