leetcode_gym/_problems/guessNumberHigherOrLower.md

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