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程式語言 - LeetCode - C++ - 374. Guess Number Higher or Lower

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參考資訊：
https://algo.monster/liteproblems/374
https://www.cnblogs.com/grandyang/p/5666502.html

題目：


解答：

/** 
 * 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);
 */

class Solution {
public:
    int guessNumber(int n) {
        long left = 0;
        long right = n;
        
        while (left < right) {
            int v = left + ((right - left) / 2);

            int r = guess(v);
            if (r < 0) { 
                right = v;
            }
            else if (r > 0) {
                left = v + 1;
            }
            else {
                return v;
            }
        }

        return left;
    }
};