Submission #483710

#	Time	Username	Problem	Language	Result	Execution time	Memory
483710		sam571128	Anagramistica (COCI21_anagramistica)	C++17	110 / 110	144 ms	1816 KiB

anagramistica

#include <bits/stdc++.h>

#define int long long
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

using namespace std;

const int N = 2e3+5, MOD = 1e9+7;
int fact[N];

int fastpow(int n, int p){
    int res = 1;
    while(p){
        if(p&1) res = res * n % MOD;
        n = n * n % MOD;
        p >>= 1;
    }
    return res;
}

void init(){
    fact[0] = 1;
    for(int i = 1;i < N;i++)
        fact[i] = fact[i-1] * i % MOD;
}

int nCr(int n, int r){
    if(n < r) return 0;
    return fact[n]*fastpow(fact[r],MOD-2)%MOD*fastpow(fact[n-r],MOD-2)%MOD;
}


signed main(){
    fastio
    init();
    int n,k;
    cin >> n >> k;

    map<string,int> m;
    for(int i = 0;i < n;i++){
        string s;
        cin >> s;
        sort(s.begin(),s.end());
        m[s]++;
    }

    vector<int> v;
    v.push_back(0);
    for(auto [a,b] : m){
        v.push_back(b);
    }

    n = v.size();
    int dp[n][k+1] = {};
    dp[0][0] = 1;

    for(int a = 1;a < n;a++){
        for(int j = k;~j;j--){
            dp[a][j] = dp[a-1][j];
        }
        int x = v[a];
        for(int i = 1;i <= x;i++){
            int tmp = i*(i-1)/2;    
            for(int j = k;~j;j--){
                if(j < tmp) break;
                dp[a][j] = (dp[a][j] + dp[a-1][j-tmp]*nCr(x,i)) % MOD; \
            }
        }
    }

    cout << dp[n-1][k] << "\n";
}   

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 70 / 70