题解 | #求平方根#

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param x int整型 
     * @return int整型
     */
    int sqrt(int x) {
        // write code here
        if (x == 0) return 0;
        int left = 1, right = x / 2 + 1;
        while (left <= right) {
            long long mid = left + (right - left) / 2;
            long long sq = mid * mid;
            if (sq == x) return mid;
            if (sq < x) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        return right;
    }
};