Day 46.1.txt

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 3 possible results:

-1: The number I picked is lower than your guess (i.e. pick < num).
1: The number I picked is higher than your guess (i.e. pick > num).
0: The number I picked is equal to your guess (i.e. pick == num).
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
Example 4:

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

Constraints:

1 <= n <= 231 - 1
1 <= pick <= n


public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int i=0,j=n-1,m;
        while(i<j)
        {
            m=i+(j-i)/2;
            if(guess(m)==0)
                return m;
            else if(guess(m)==1)
                i=m+1;
            else
                j=m-1;
        }
        return i;
    }
}