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.
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
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
To fix the errors in the code, we need to make two changes:
1. Add a condition to exit the while loop when the secret number is found.
2. Modify the guess variable when the sign is -1 to divide it by 2 instead of multiplying it by 2.
Here is the corrected code:
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) == 0:
return guess
foundNumber = False
while not foundNumber:
sign = isMyNumber(guess)
if sign == -1:
guess //= 2
elif sign == 1:
guess += 1
else:
foundNumber = True
return guess
Now, the code will correctly return the secret number when found.
To fix the errors in the code so that `jumpAndBackpedal` correctly returns the secret number, we need to modify the while loop condition and update the guess variable inside the loop.
The issue in the given code is that the while loop condition `while not foundNumber` is always true, causing an infinite loop. This is because the `foundNumber` variable is never updated inside the loop.
To fix this, we can update the while loop condition to check if the sign returned by `isMyNumber` is not equal to 0. If it is not equal to 0, it means we have found the secret number.
Here is the updated code:
```python
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) == 0:
return guess
foundNumber = False
while isMyNumber(guess) != 0:
sign = isMyNumber(guess)
if sign == -1:
guess *= 2
else:
guess -= 1
return guess
```
In the updated code, we check if `isMyNumber(guess)` is equal to 0 inside the `if` statement to return the guess directly. If it is not equal to 0, we continue with the while loop until the sign is 0.