Leetcode 69: Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

x is guaranteed to be a non-negative integer.

Example 1:

Input: 4
Output: 2

 

Example 2:

Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since we want to return an integer, the decimal part will be truncated.

 

 Note: BinarySearch is easy to understand but difficult to be bug free.

public class Solution {
    public int MySqrt(int x) {
        if (x <= 1) return x;
        
        int low = 1, high = x;
        while (low < high)
        {
            int mid = low + (high - low) / 2;
            if (mid == x / mid)
            {
                return mid;
            }
            else if (mid > x / mid)
            {
                high = mid;
            }
            else
            {
                low = mid + 1;
            }
        }
        
        return low - 1;
    }
}