Leetcode 374. Guess Number Higher or Lower

374. Guess Number Higher or Lower

アプローチ

二分探索

O(log n)

/** 
 * Forward declaration of guess API.
 * @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
 * int guess(int num);
 */

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int start = 1;
        int end = n;

        while(start <= end){
            int mid = start + (end- start) / 2;
            int check = guess(mid);
            if(check == 0){
                return mid;
            }else if(check == 1) {
                 start = mid + 1;
            }else{   
                 end = mid -1;
            }
        }
        return 0;
    }
}