LeetCode 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’ll tell you whether the number is higher or lower. You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower
 1 : My number is higher
 0 : Congrats! You got it!

Example:

n = 10, I pick 6.
Return 6.

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简单的猜数字游戏。使用二分搜索就好。唯一需要注意的是，题目中的guess函数中说My number is lower/higher是指正确答案比中值低或高，而不是我们猜的中值比正确答案低或高。唉，这算是题目描述不清吧，为此WA两次。 代码如下： [cpp] int guess(int num); class Solution { public: int guessNumber(int n) { int l = 1, r = n, mid = l + (r – l) / 2; int g = guess(mid); while (g != 0) { if (g == -1)r = mid – 1; else l = mid + 1; mid = l + (r – l) / 2; g = guess(mid); } return mid; } }; [/cpp] 本代码提交AC，用时0MS。]]>