leetocde 374. Guess Number Higher or Lower

原题：

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.

最简单的猜数字，二分查找。

不写不知道，还是leetcode的数值极限玩的好。

代码：

// Forward declaration of guess API.// @param num, your guess// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0int guess(int num);class Solution {public:    int guessNumber(int n) {        int flag=0;        long int test;        long int l1=1;        long int l2=n;        do        {            test=(l1+l2)/2;            int t=guess((int)test);            printf("%dA",test);            switch(t)            {                case -1:                {                    l2=l2-(l2-l1)/2;                    break;                }                case 0:                {                    flag=1;                    break;                }                case 1:                {                    if(l1==(int)(l1+(l2-l1)/2))                        l1=l1+1;                    else                        l1=l1+(l2-l1)/2;                    break;                }                default:                    break;            }        }        while(flag!=1);        return test;    }};

写的还算比较清晰吧，不过就是在数值极致点卡了一会