I am new at CP, and have only given one contest Can someone please help me and tell me what is wrong in my approach for the question 431C - k-Tree. I am trying Dynamic Programming.

```
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
const int MOD = 1000000007;
vector<vector<int>> memo;
int dp(int k, int n, int d, int found)
{
if(n==0)
{
if(found) return 1;
else return 0;
}
if(n<0)
{
return 0;
}
if(memo[n][found]!=-1)
{
return memo[n][found];
}
int total = 0;
for(int i=1; i<=k; i++)
{
if(n-i < 0) break;
total = (total%MOD + dp(k, n-i, d, found || i>=d)%MOD)%MOD;
}
return memo[n][found] = total%MOD;
}
int32_t main()
{
int k, n, d;
cin >> k >> n >> d;
memo = vector<vector<int>>(n+1, vector<int>(2, -1));
cout << dp(k, n, d, 0) << "\n";
return 0;
}
```

Fails on Test case 5: ` 4 3 2 `

Expected: `6`

Output: `3`

do cin >> n >> k >> d;

oops, i wanna cry over such a mistake

Thank You so much for help: omar1312

you're welcome :)

Bro I am facing problem in new question

please help me

My Blog For Discussion

Apart from your question, which I think was resolved, a side note you can observe is that this problem really is a knapsack in disguise. This is same as having an unlimited supply of numbers in the range 1 to k and we are suppose to count ways in which we can sum numbers to n, while using an element >= d at least once. You can prove that each path in the tree which sums to $$$n$$$ and each solution to $$$x_1 + x_2 +... x_j = n$$$ has a one to one correspondence.

Such a problem will have an implementation like this:unbounded knapsack indeed Aspergillus :)

Bro I am facing problem in new question

please help me

My Blog For Discussion

sorry man a little tired right now, also I prefer iterative dp over memoisation unless I literally cant do it any other way so yeah... maybe check out my solution? I think I added a comment for understanding, it's clean too look at it once this if you wish.