CSES - Shared codeLink to this code:
https://cses.fi/paste/c6b2bb30bc35247f450a97/
//! We can go up or down, either ways I am prepared
//! Hello there! Subhadeep this side.
#include<bits/stdc++.h>
using namespace std;
#define fastio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define MOD 1000000007
#define MOD1 998244353
#define INF 1e18
#define nline "\n"
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define ff first
#define ss second
#define PI 3.141592653589793238462
#define set_bits __builtin_popcountll
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define mid(low, high) (low + ((high - low) >> 1))
typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;
// typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update > pbds; // find_by_order, order_of_key
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x <<" "; _print(x); cerr << endl;
#else
#define debug(x)
#endif
void _print(ll t) {cerr << t;}
void _print(int t) {cerr << t;}
void _print(string t) {cerr << t;}
void _print(char t) {cerr << t;}
void _print(lld t) {cerr << t;}
void _print(double t) {cerr << t;}
void _print(ull t) {cerr << t;}
template <class T, class V> void _print(pair <T, V> p);
template <class T> void _print(vector <T> v);
template <class T> void _print(set <T> v);
template <class T, class V> void _print(map <T, V> v);
template <class T> void _print(multiset <T> v);
template <class T, class V> void _print(pair <T, V> p) {cerr << "{"; _print(p.ff); cerr << ","; _print(p.ss); cerr << "}";}
template <class T> void _print(vector <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(set <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T> void _print(multiset <T> v) {cerr << "[ "; for (T i : v) {_print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void _print(map <T, V> v) {cerr << "[ "; for (auto i : v) {_print(i); cerr << " ";} cerr << "]";}
template<class T> inline T nxt(T) {
T x;
cin >> x;
return x;
}
ll n, target;
ll coins[105];
ll dp[105][1000100];
int answer(int level, int goal) {
// pruning
// base case
if(goal == target) return 1;
if(level >= n) return 0;
// cache check
if(dp[level][goal] != -1) return dp[level][goal];
// transition / compute
int take = 0, nottake = 0;
if(goal + coins[level] <= target)
take += answer(level, goal + coins[level]);
nottake += answer(level+1, goal);
// save and return
dp[level][goal] = take + nottake;
return dp[level][goal];
}
void solve() {
cin >> n >> target;
for (int i = 0; i < n; i++) cin >> coins[i];
memset(dp, -1, sizeof(dp));
cout << answer(0,0) << nline;
}
int main() {
#ifndef ONLINE_JUDGE
freopen("Error.txt", "w", stderr);
#endif
fastio();
int t=1;
// cin>>t;
while(t--) {
solve();
}
return 0;
}