Sqrt

Given a non-negative integer x, return the square root of x rounded down to the nearest integer. The returned integer should be non-negative as well.

You must not use any built-in exponent function or operator. For example, do not use pow(x, 0.5) in C++ or x ** 0.5 in Python.

Example 1:

• Input: x = 4
• Output: 2

Example 2:

• Input: x = 8
• Output: 2

class Solution {
    public int mySqrt(int x) {
        if (x < 2) {
            return x;
        }
        var l = 1;
        var r = x / 2;
        while (l <= r) {
            int mid = l + (r - l) / 2;
            long prod = (long) mid * mid;
            if (prod == x) {
                return mid;
            } else if (prod > x) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        return r;
    }
}