So in this problem i am trying to solve it using dynamic programming approach. But I am unable to understand the solution since its written in poor english. I am referring to this tutorial. How is the dp[][] being developed?. it will be great if someone could explain in details since i am a newbie. Thank you in advance!

include

include <stdio.h>

include

using namespace std;

const int mod = 1e9 + 7;

int dp[100][2];

void add(int &a, int b) { a += b; if(a >= mod) a -= mod; }

int main(int argc, char ** argv) { int n, k, d; cin >> n >> k >> d; dp[0][0] = 1; dp[0][1] = 0;

for(int i = 1 ; i <= n ; ++i)
{
    dp[i][0] = dp[i][1] = 0;

    for(int j = 1 ; j <= k ; ++j)
    {
        if(i-j < 0) break;

        if(j < d)
        {
            add(dp[i][0], dp[i-j][0]);
            add(dp[i][1], dp[i-j][1]);
        }
        else
        {
            add(dp[i][1], dp[i-j][0]);
            add(dp[i][1], dp[i-j][1]);
        }
    }
}
cout << dp[n][1] << "\n";
return 0;

}