---
layout: page
title:  Guess Number Higher or Lower
last_solved: 
category: binary search
leetcode_url: https://leetcode.com/problems/guess-number-higher-or-lower
status: Attempted
---

Problem
-------

```
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 :

Input: n = 10, pick = 6
Output: 6

```

Solution
----------

Simplist binary search ever

{% highlight python %}

def guessNumber(self, n: int) -> int:
    
    low, high = 1, n
    
    while low<=high:
        
        mid = (low+high)//2
        
        if guess(mid)==0:
            return mid
        elif guess(mid)==-1:
            high = mid-1
        else:
            low = mid+1
    
    return None

{% endhighlight %}

__________

{% highlight python %}

def guessNumber(self, n: int) -> int:
    
    left, right = 1, n
    
    while left<right:
        
        mid = (left+right)//2
        
        result = guess(mid)
        
        if result<=0:
            right = mid       # target is lower, so ignore everything on the right
        else:
            left = mid+1
    
    return left

{% endhighlight %}

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