You have a total
of N coins that you want to form in a staircase shape, where every k-th row
must have exactly k coins. Given N, find the total number of full staircase
rows that can be formed.
Input
Format:
The first line
contains N.
Output
Format:
Single line
containing number of full staircase rows.
Boundary
Conditions: N is a non-negative integer and fits within the range
of a 32-bit signed integer.
Example
Input/Output 1:
Input:
5
Output:
2
Explanation:
The coins can form
the following rows:
¤
¤ ¤
¤ ¤
Because the 3rd
row is incomplete, we return 2.
Solution:
#include
<iostream>
#include
<math.h>
using namespace
std;
int main()
{
long int n;
cin>>n;
cout<<(int)((-1 + sqrt(1 + 8 *n))/2);
return 0;
}