solution link → https://cses.fi/paste/4060ef4da6056bb522a9ca/

IN my case i am calling solve() function on when some coin[i]<= sum so sum should never be less than zero right .

for example suppose we have only coin 7 and we have to find number of permutation for 5

solve(5) → no coin less than equal to 5 so g=0

dp[5]=0;

function will end.

Recursive calls make your code slower. Whenever possible, avoid using recursion and try to solve dp problems iteratively.

```
#include <bits/stdc++.h>
using namespace std;
const int md = 1e9 + 7;
int main() {
int n,x;
cin >> n >> x;
vector<int> a(n);
for(int i = 0;i < n;i++){
cin >> a[i];
}
vector<int> dp(x+1);
dp[0] = 1;
for(int j = 0;j <= x;j++){
for(int i = 0;i < n;i++){
if(j >= a[i]){
dp[j] += dp[j-a[i]];
if(dp[j] >= md)dp[j] -= md;
}
}
}
cout << dp[x];
return 0;
}
```