69. Sqrt(x)

Implement int sqrt(int x).

Compute and return the square root of x.

Overflow when mid * mid, use divide instead.

public class Solution {
    public int mySqrt(int x) {
        if(x == 0 || x == 1) return x;
        int l =0;
        int r = x;
        while(l <= r){
            int mid = l +(r-l)/2;
            if( x/mid == mid ) return mid;
            else if( x/mid < mid){
                r = mid -1;
            }else{
                l = mid+1;
            }
        }
        return r;
    }
}