LeetCode Problem
374. Guess Number Higher or Lower
Link to LeetCode
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 (the number I picked stays the same throughout the game).
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
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* int guess(int num);
*/
public class Solution extends GuessGame {
public int guessNumber(int n) {
int start = 1;
while(start <= n) {
int mid = start + ((n-start)/2);
int num = guess (mid);
if (num == 0) {
return mid;
} else if (num == -1) {
n = mid-1;
} else {
start = mid+1;
}
}
return start;
}
}