374. Guess Number Higher or Lower

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 will tell you whether the number I picked is higher or lower than your guess.

You call a pre-defined API int guess(int num), which returns three possible results:

• -1: Your guess is higher than the number I picked (i.e. num > pick).
• 1: Your guess is lower than the number I picked (i.e. num < pick).
• 0: your guess is equal to the number I picked (i.e. num == pick).

Return the number that I picked.

 

Example 1:

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

Example 2:

Input: n = 1, pick = 1
Output: 1

Example 3:

Input: n = 2, pick = 1
Output: 1

 

Constraints:

• 1 <= n <= 231 - 1
• 1 <= pick <= n

---

# The guess API is already defined for you.
# @param num, your guess
# @return -1 if num is higher than the picked number
#          1 if num is lower than the picked number
#          otherwise return 0
# def guess(num: int) -> int:

class Solution:
    def guessNumber(self, n: int) -> int:
        cmin=0
        cmax=n
        cmid=(cmin+cmax)//2
        gResult = guess(cmid)
        while True:    
            if gResult==1:
                cmin=cmid
                cmid=(cmin+cmax+1)//2
            elif gResult==-1:
                cmax=cmid+1
                cmid=(cmin+cmax)//2
            gResult=guess(cmid)
            if gResult==0:
                return (cmid)