[Leetcode] Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

[解题方法]

二分法，注意溢出的处理方法

[代码]

class Solution {
public:
    int sqrt(int x) {
        if (x < 0) return -1;
        if (x == 0) return 0;
        if (x <= 3) return 1;
        
        int left = 1;
        int right = x / 2 + 1;
        
        while (left <= right) {
            int mid = (left + right) / 2;
            if (mid <= x / mid && (mid + 1) > x / (mid + 1)) {
                return mid;
            } else if (mid > x / mid) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        
        return -1;
    }
};