leetcode441

public class Solution {
    public int ArrangeCoins(int n) {
        //convert int to long to prevent integer overflow
            long nLong = (long)n;
            long st = ;
            long ed = nLong;
            long mid = ;
            while (st <= ed)
            {
                mid = st + (ed - st) / ;

                if (mid * (mid + ) <=  * nLong)
                {
                    st = mid + ;
                }
                else
                {
                    ed = mid - ;
                }
            }
            return (int)(st - );
    }
}

https://leetcode.com/problems/arranging-coins/#/description