Could someone explain this idea?
tbl[0] = 1;
for (int i = 1; i <= N; i++)
{
    for (int j = N; j >= i ; j--)
    {
            tbl[j] += tbl[j-i];
    }
}
cout<<tbl[N]-1<<endl;

It is compressed 2-dimensional dynamic programming state.
It is like we take staircase from 1,2,...,N cubes and add one more step.
Subtract one to not count zero len staircase.

Edited by author 08.07.2017 16:20

"Compressed " means that say dp[x] = Sum(dp[x] [i]) {i = 0,1,...,N}

Edited by author 08.07.2017 16:20

Edited by author 08.07.2017 16:22