LeetCode（69）——Sqrt(x)

题目：

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.

AC：

class Solution {
    public int mySqrt(int x) {
		if (x <= 1) {
            return x;
        }
            
        int left = 1;
		int right = x;
		int mid = 0;
		
		while (left + 1 < right) {
			mid = left + ((right - left) >> 1);
			
			if (mid == x / mid) {
				return mid;
			}
			else if (mid > x / mid) {
				right = mid;
			}
			else {
				left = mid;
			}
		}
		
		return left;
	}
}