# Leetcode: Guess Number Higher or Lower

Guess number quickly

Similar Problems:

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I’ll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

```-1 : My number is lower
1 : My number is higher
0 : Congrats! You got it!
```

Example:

```n = 10, I pick 6.

Return 6.
```

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

```## Blog link: https://code.dennyzhang.com/guess-number-higher-or-lower
## Basic Ideas: binary search
##      1 1 1 0 -1 -1 -1
## Complexity: Time O(log(n)), Space O(1)

# The guess API is already defined for you.
# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
# def guess(num):

class Solution(object):
def guessNumber(self, n):
"""
:type n: int
:rtype: int
"""
left, right = 1, n
while left <= right:
mid = int(left + (right-left)/2)
v = guess(mid)
if v == 0:
return mid
elif v == 1:
left = mid + 1
else:
right = mid - 1
return None
```

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