题目链接

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.

解题思路

TODO （稍后补充）

解题代码

// Forward declaration of guess API.
// @param num, your guess
// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num);

class Solution {
public:
    int guessNumber(int n) {
        int myGuessNum = 1 + (n-1)/2;
        int begin = 1;
        int end = n;
        while(1) {
            int tip = guess(myGuessNum);
            if (tip == 0) break;
            if (tip < 0) {
                end = myGuessNum-1;
                myGuessNum = begin + (end - begin)/2;
                //myGuessNum = (begin + end)/2;
            }
            else {
                begin = myGuessNum+1;
                myGuessNum = begin + (end - begin)/2;
                //myGuessNum = (begin + end)/2;
            }
        }
        return myGuessNum;
    }
};