69. Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

题目题目：返回一个int数开方后的结果

    public int mySqrt(int x) {
        if (x == 0)
            return 0;
        int left = 1, right = x;
        int ans = 1;
        while (left<=right)
        {
            int mid = left+ (right-left)/2;
            if (mid == x/mid)
            {

                return mid;
            }
            else if (mid>x/mid) right=mid-1;
            else left=mid+1;
        }
        return right;     
    }