Number guessing game (the computer plays) in Python.

The program

Press Run to see what it prints. Change anything you like, then run it again.

secret = 73
low, high = 1, 100
guesses = 0
while True:
    guess = (low + high) // 2
    guesses = guesses + 1
    if guess == secret:
        print("Found", guess, "in", guesses, "guesses")
        break
    elif guess < secret:
        print(guess, "is too low")
        low = guess + 1
    else:
        print(guess, "is too high")
        high = guess - 1

50 is too low
75 is too high
62 is too low
68 is too low
71 is too low
Found 73 in 6 guesses

How it works

1. Instead of asking a person, the program plays by itself. Each guess is the middle of the numbers that are still possible, so the number of possibilities halves every time.
2. This is called binary search. With 100 numbers it never needs more than 7 guesses, because 2 to the power of 7 is 128.
3. while True loops forever, and break is the way out.

Try this

• Change the secret number and see how many guesses it takes.
• Find the largest number of guesses for any secret from 1 to 100.
• Make it work for numbers up to 1000.

Stuck on an error? Read how to debug Python.