LeetCode 374 Guess Number Higher or Lower
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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.
这道题略坑，my number指的是最后的正确答案，而不是你猜测的值。同时在二分搜索的时候要注意，mid可以有两种计算方法，但第一种由于low + high超出int范围而超时。
mid = (low + high) / 2;
mid = low + (high - low) / 2;
代码如下：
public int guessNumber(int n) {
int low = 1, high = n;
while (low < high) {
int mid = low + (high - low)/2;
int cmp = guess(mid);
if (cmp == 0) return mid;
else if (cmp == 1) {
low = mid + 1;
} else {
high = mid - 1;
}
}
return low;
}
