Leetcode 69. Sqrt(x)

public class Solution {
public int mySqrt(int x) {
long low = 0, high = x;
while (low + 1 < high) {
long mid = low + (high-low)/2;
if (mid * mid > x) high = mid;
else low = mid;
}
if (high * high <= x) return (int) high;
return (int) low;
}
}