Sqrt(x)

Easy Sqrt(x)

24%

Accepted

Implement int sqrt(int x).

Compute and return the square root of x.

Have you met this question in a real interview? 

Yes

Example

sqrt(3) = 1

sqrt(4) = 2

sqrt(5) = 2

sqrt(10) = 3

Challenge

O(log(x))

class Solution {

    /**

     * @param x: An integer

     * @return: The sqrt of x

     */

    public int sqrt(int x) {

        // write your code here

        long lo = 0, hi = x/2 + 1;

        while(lo <= hi){

             long mid = (hi+lo)/2;

            if (x < mid * mid) {

                hi = mid-1;      // not hi = mid

            } else if(x > mid * mid) {

                lo = mid+1;  

            } else return (int) mid;

        }

        return (int) hi;

    }

}
Solution:
class Solution {
    /**
     * @param x: An integer
     * @return: The sqrt of x
     */
    public int sqrt(int x) {
        // write your code here
        if(x <= 0) return x;
        double last = 0, cur = 1;
        while(last != cur){
            last = cur;
            cur = (cur + x/cur)/2;
        }
        return (int) cur;
    }

}