Submission #4063585

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MOD = 1000000007;

signed main(){

    int n, x; cin >> n >> x;
    string s; cin >> s;
    //番兵
    s.push_back('m');
    n = (int)s.size();
    vector<vector<vector<int> > > dp(n + 2, vector<vector<int> > (x + 1, vector<int> (n + 1, 0)));
    dp[0][0][0] = 1LL;

    for(int i = 0; i < n; i++){

        //cout << s[i] << endl;
        for(int j = 0; j <= x; j++){
            for(int k = 0; k <= n; k++){
                if(dp[i][j][k] == 0) continue;

                if(s[i] == '2' || s[i] == '?'){
                    if(k % 2 == 0){
                        (dp[i + 1][j][k + 1] += dp[i][j][k]) % MOD;
                    }else{
                        int num = k / 2;
                        int sum = ((1 + num) * num) / 2;
                        if(j + sum <= x) (dp[i + 1][j + sum][1] += dp[i][j][k]) % MOD;
                    }
                }
                
                if(s[i] == '5' || s[i] == '?'){
                    if(k % 2 == 1){
                        (dp[i + 1][j][k + 1] += dp[i][j][k]) % MOD;
                    }else{
                        int num = k / 2;
                        int sum = ((1 + num) * num) / 2;
                        if(j + sum <= x) (dp[i + 1][j + sum][0] += dp[i][j][k]) % MOD;
                    }
                }
                
                if((s[i] != '2' && s[i] != '5') || s[i] == '?'){
                    int num = k / 2;
                    int sum = ((1 + num) * num) / 2;
                    if(j + sum <= x) (dp[i + 1][j + sum][0] += dp[i][j][k]) % MOD;
                    //cout << i << " " << j << " " << k << " " << num << " " << sum << endl;
                }
            }
        }
    }

    cout << dp[n][x][0] << endl;
    return 0;
}

Submission Info

Judge Result