Sqrt(x)

Problem Description

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 (Go)

// https://leetcode.com/problems/sqrtx/discuss/25057/3-4-short-lines-Integer-Newton-Every-Language
func mySqrt(x int) int {
	r := x
	for r*r > x {
		r = (r + x/r) / 2
	}
	return r
}