Question

Answer the following question without running the code. The procedure isMyNumber is used to hide a secret number (integer). It takes an integer x as a parameter and compares it to the secret number. It returns:

-1 if the parameter x is less than the secret number

0 if the parameter x is correct

1 if the parameter x is greater than the secret number

The following procedure, jumpAndBackPedal, attempts to guess a secret number. The only way it can interact with the secret number is through the isMyNumber procedure explained above.

def jumpAndBackpedal(isMyNumber):
'''
isMyNumber: Procedure that hides a secret number.
It takes as a parameter one number and returns:
* -1 if the number is less than the secret number
* 0 if the number is equal to the secret number
* 1 if the number is greater than the secret number

returns: integer, the secret number
'''
guess = 1
if isMyNumber(guess) == 1:
return guess
foundNumber = False
while not foundNumber:
sign = isMyNumber(guess)
if sign == -1:
guess *= 2
else:
guess -= 1
return guess
Unfortunately, the implementation given does not correctly return the secret number. Please fix the errors in the code such that jumpAndBackpedal correctly returns the secret number.

Answer 1

def jumpAndBackpedal(isMyNumber):
'''
isMyNumber: Procedure that hides a secret number.
It takes as a parameter one number and returns:
* -1 if the number is less than the secret number
* 0 if the number is equal to the secret number
* 1 if the number is greater than the secret number

returns: integer, the secret number
'''

guess = 1
foundNumber = False
while not foundNumber:
sign = isMyNumber(guess)
if sign == -1:
guess *= 2
elif sign == 1:
guess -= 1
elif sign == 0:
foundNumber =True
return guess

Answer 2

def jumpAndBackpedal(isMyNumber):
'''
isMyNumber: Procedure that hides a secret number.
It takes as a parameter one number and returns:
* -1 if the number is less than the secret number
* 0 if the number is equal to the secret number
* 1 if the number is greater than the secret number

returns: integer, the secret number
'''
if isMyNumber(0) == 1:
return 0
guess = 1;
foundNumber = False
while not foundNumber:
sign = isMyNumber(guess)
if sign == -1:
guess *= 2
elif sign == 1:
guess -= 1
else:
foundNumber = True;
return guess