441. Arranging Coins

Java

public class Solution {
    public int arrangeCoins(int n) {
        int result=0;
        int count=1;
        while(n>0)
        {
            if(n-count>=0)
            result++;
            n=n-count;
            count++;
        }
        return result;
    }
}

Java

public class Solution {
    public int arrangeCoins(int n) {
        return (int)((-1 + Math.sqrt(1 + 8 * (long)n)) / 2);
    }
}