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Submission #483710

# Submission time Handle Problem Language Result Execution time Memory
483710 2021-10-31T23:40:31 Z sam571128 Anagramistica (COCI21_anagramistica) C++17
110 / 110
 144 ms 1816 KB 
#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
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 0 ms 204 KB Output is correct
3 Correct 0 ms 204 KB Output is correct
4 Correct 0 ms 204 KB Output is correct
5 Correct 0 ms 204 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 332 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 2 ms 376 KB Output is correct

Subtask #3
70.0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 0 ms 204 KB Output is correct
3 Correct 0 ms 204 KB Output is correct
4 Correct 0 ms 204 KB Output is correct
5 Correct 0 ms 204 KB Output is correct
6 Correct 1 ms 332 KB Output is correct
7 Correct 1 ms 332 KB Output is correct
8 Correct 1 ms 332 KB Output is correct
9 Correct 2 ms 376 KB Output is correct
10 Correct 30 ms 716 KB Output is correct
11 Correct 12 ms 364 KB Output is correct
12 Correct 1 ms 332 KB Output is correct
13 Correct 12 ms 340 KB Output is correct
14 Correct 20 ms 472 KB Output is correct
15 Correct 8 ms 332 KB Output is correct
16 Correct 87 ms 1816 KB Output is correct
17 Correct 144 ms 460 KB Output is correct
18 Correct 1 ms 332 KB Output is correct