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.
這道題略坑辩稽，my number指的是最后的正確答案，而不是你猜測(cè)的值谍肤。同時(shí)在二分搜索的時(shí)候要注意灾茁，mid可以有兩種計(jì)算方法若河，但第一種由于low + high超出int范圍而超時(shí)调限。
mid = (low + high) / 2;
mid = low + (high - low) / 2;
代碼如下：
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;
}
