Sqrt(x)

对于我这种没什么数学本事的人来说，什么牛顿迭代啊，不会！所以这种办法简单粗暴但是又有效……

class Solution {public:    int sqrt(int x) {        if (x <= 0)            return 0;        for (int i = 0; ; ++i) {            long long mul = (long long) i * i;            if (mul > (long long)x)                return i - 1;        }    }};

http://oj.leetcode.com/problems/sqrtx/