Sqrt(x) -- LeetCode (Java)

public int sqrt(int x) {
        if(x==0){
            return 0;
        }
        if(x<0){
            return -1;
        }
        int l = 1;
        int r = x;
        while(l<=r){
            int m = l + (r-l)/2;
            if(x/m==m){
                return m;
            }else if(x/m>m){
                l=m+1;
            }else{
                r=m-1; 
            }
        }
        return r;
        
    }