# 69. Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x, where x is guaranteed to be a non-negative integer.

Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.

Example 1:

Input: 4
Output: 2

Example 2:

Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since 
             the decimal part is truncated, 2 is returned.

# Solution

Approach 1: Binary search.

# Code (Python)

Approach 1:

# Code (C++)

Approach 1:

class Solution {
public:
    int mySqrt(int x) {
        int head = 0;
        int tail = x;
        while (head <= tail)
        {
            long mid = head + (tail - head) / 2;
            long square = mid * mid;
            if (square == x)
                return mid;
            else if (square < x)
                head = mid + 1;
            else
                tail = mid - 1;
        }
        return head - 1;
    }
};