69. Sqrt(x)

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 Explanation: The square root of 4 is 2, so we return 2.

Example 2: Input: x = 8 Output: 2 Explanation: The square root of 8 is 2.82842..., and since we round it down to the nearest integer, 2 is returned.

Constraints:

• 0 <= x <= 231 - 1

Solution:

/**
 * @param {number} x
 * @return {number}
 */
var mySqrt = function(x) {
    if (x < 2) return x
    var l = 1
    var r = x
    while (l <= r) {
        m = l + ((r - l) / 2) ^ 0
        if(m > x / m) {
            r = m - 1
        } else if ((m + 1) > x / (m + 1)) {
            return m
        } else l = m + 1
    }
};