Submission #679909

#	Time	Username	Problem	Language	Result	Execution time	Memory
679909		Shadii_usf	Anagramistica (COCI21_anagramistica)	C++14	0 / 110	4 ms	620 KiB

anagramistica

#include <bits/stdc++.h>
using namespace std;
const int maxn =  2e3 + 10, mod = 1e9 + 7;
long long dp[maxn][maxn] , f[maxn] , invf[maxn]  , anss;
long long power(int a , int b){
    if(b == 0){
        return 1;
    }
    anss = power(a , b/2);
    anss *= anss;
    anss %= mod;
    if(b & 1){
        anss *= a;
        anss %= mod;
    }
    return anss;
}
long long c(int n , int k){
    return f[n] * invf[k] % mod * invf[n - k] % mod;
}
int main(){
    int n , k , cnt = 1 , sizee;
    string a[maxn];
    bool mark[maxn] , markk[maxn];
    vector <int> v;
    cin >> n >> k;
    for(int i=1 ; i<=n ; i++){
        cin >> a[i];
    }
    for(int i=1 ; i<=n ; i++){
        sizee = a[i].size();
        for(int j = 0 ; j<sizee ; j++){
            mark[a[i][j] - 'a'] = true;
        }
        for(int j = 1 ; j<=n ; j++){
            bool x = true;
            if(!markk[j] && j != i){
                int sizee = a[j].size();
                for(int k = 0 ; k<sizee ; k++){
                    if(!mark[a[j][k] - 'a']){
                        x = false;
                        break;
                    }
                }
                if(x){
                    cnt++;
                    markk[j] = true;
                }
            }
        }
        if(!markk[i]){
            v.push_back(cnt);
            markk[i] = true;
        }
        sizee = a[i].size();
        for(int j = 0 ; j<sizee ; j++){
            mark[a[i][j] - 'a'] = false;
        }
        cnt = 1;
    }
    f[0] = invf[0] = 1;
    for(int i=1 ; i<maxn ; i++){
        f[i] = f[i-1] * i;
        f[i] %= mod;
        invf[i] = power(f[i] , mod - 2);
    }
    for(int i=0 ; i<=v[0] ; i++){
        int num = (i * (i - 1))/2;
        dp[0][num] = c(v[0] , i);
    }
    sizee = v.size();
    for(int i=1 ; i<sizee ; i++){
        for(int j=0 ; j<=k ; j++){
            int m = 0;
            while((m * (m - 1))/2 <= j && m <= v[i]){
                dp[i][j] += (dp[i - 1][j - (m * (m - 1))/2] * c(v[i] , m) % mod);
                dp[i][j] %= mod;
                m++;
            }
        }
    }
    sizee = v.size();
    cout << (dp[sizee - 1][k] == 0 ? -1 : dp[sizee - 1][k]);
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 30
• Subtask 3: 0 / 70