Submission

Score: 100

User: SnowAveNode

Problemset: กองไฟ

Language: cpp

Time: 0.004 second

Submitted On: 2026-04-22 18:49:09

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const int nx = 1e5 + 5, MOD = 1e9 + 7, inf = 2e9; const ll INF = 4e18;

ll dp[2][52][52][3][3];

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr);

    int n,na,nb,nc; cin>>n>>na>>nb>>nc;
    if(na>n/2 || nb>n/2 || nc>n/2) return cout<<0,0;

    dp[0][1][0][0][0] = 1;
    dp[0][0][1][1][1] = 1;
    dp[0][0][0][2][2] = 1;

    for(int i=0; i<n-1; i++) {
        int cur = i % 2, next = (i+1) % 2;
        memset(dp[next], 0, sizeof(dp[next]));
        for(int a=0; a<=na; a++) {
            for(int b=0; b<=nb; b++) {
                int c = i+1-a-b;
                if(c<0 || c>nc) continue;
                for(int prev=0; prev<3; prev++) {
                    for(int first=0; first<3; first++) {
                        ll val = dp[cur][a][b][prev][first];
                        if(val == 0) continue;
                        if(a<na && prev!=0) dp[next][a+1][b][0][first] = (dp[next][a+1][b][0][first] + val) % MOD;
                        if(b<nb && prev!=1) dp[next][a][b+1][1][first] = (dp[next][a][b+1][1][first] + val) % MOD;
                        if(c<nc && prev!=2) dp[next][a][b][2][first] = (dp[next][a][b][2][first] + val) % MOD;
                    }
                }
            }
        }
    }

    ll ans=0;
    for(int prev=0; prev<3; prev++) {
        for(int first=0; first<3; first++) {
            if(prev==first) continue;
            int last=(n-1)%2;
            ans = (ans + dp[last][na][nb][prev][first]) % MOD;
        }
    }
    cout << ans % MOD << '\n';

    return 0;
}