69. Sqrt(x) - jiejackyzhang/leetcode-note GitHub Wiki

Implement int sqrt(int x).

Compute and return the square root of x.

解题思路为binary search。

public class Solution {
    public int mySqrt(int x) {
        if(x < 0) return x;
        if(x == 0) return 0;
        int left = 1, right = x;
        while(left <= right) {
            int mid = left + (right - left) / 2;
            if(mid == x / mid) {
                return mid; // mid * mid may overflow
            } else if(mid > x / mid) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return right;
    }
}