oj.uz

Submission #494330

# Submission time Handle Problem Language Result Execution time Memory
494330 2021-12-15T06:53:08 Z AlperenT Anagramistica (COCI21_anagramistica) C++17
110 / 110
 17 ms 460 KB 
#include <bits/stdc++.h>

using namespace std;

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

struct mint{
    int val;

    mint(long long a = 0) : val(a % MOD) {if(val < 0) val += MOD; }
    mint(long long a, long long b) {*this += a, *this /= b; }

    mint &operator += (const mint &b) {val += b.val; if(val >= MOD) val -= MOD; return *this; }
    mint &operator -= (const mint &b) {val -= b.val; if(val < 0) val += MOD; return *this; }
    mint &operator *= (const mint &b) {val = (1ll * val * b.val) % MOD; return *this; }

    mint mexp(mint a, long long b){
        mint c(1);
        for(; b > 0; b /= 2, a *= a) if(b & 1) c *= a;
        return c;
    }

    mint minv(const mint &a) {return mexp(a, MOD - 2); }

    mint &operator /= (const mint &b) {return *this *= minv(b); }

    friend mint operator + (mint a, const mint &b) {return a += b; }
    friend mint operator - (mint a, const mint &b) {return a -= b; }
    friend mint operator * (mint a, const mint &b) {return a *= b; }
    friend mint operator / (mint a, const mint &b) {return a /= b; }

    friend bool operator == (const mint &a, const mint &b) {return a.val == b.val; }
    friend bool operator != (const mint &a, const mint &b) {return a.val != b.val; }

    friend istream &operator >> (istream &is, mint &a) {long long b; is >> b; a = b; return is; }
    friend ostream &operator << (ostream &os, const mint &a) {return os << a.val; }
};

int n, k, paircnt;

mint fact[N], invfact[N], knap[N], knap2[N];

vector<pair<int, mint>> v;

bool isknap[N], isknap2[N];

map<string, int> mp;
string str;

mint comb(int a, int b){
    return fact[a] * (invfact[b] * invfact[a - b]);
}

void precalc(){
    fact[0] = 1;
    for(int i = 1; i < N; i++) fact[i] = fact[i - 1] * i;

    invfact[N - 1] = mint(0).minv(fact[N - 1]);
    for(int i = N - 2; i >= 0; i--) invfact[i] = invfact[i + 1] * (i + 1);
}

int main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);

    precalc();

    cin >> n >> k;

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

        sort(str.begin(), str.end());

        mp[str]++;
    }

    isknap[0] = true;
    knap[0] = 1;

    for(auto p : mp){
        v.clear();

        for(int i = 1; i <= p.second; i++){
            paircnt = (i * (i - 1)) / 2;

            if(paircnt < N) v.push_back({paircnt, comb(p.second, i)});
        }

        fill(knap2, knap2 + N, 0);
        memset(isknap2, 0, sizeof(isknap2));

        for(auto itm : v){
            for(int i = N - 1; i >= itm.first; i--){
                if(isknap[i - itm.first]){
                    isknap2[i] = true;
                    knap2[i] += knap[i - itm.first] * itm.second;
                }
            }
        }

        for(int i = 0; i < N; i++) isknap[i] |= isknap2[i], knap[i] += knap2[i];
    }

    cout << knap[k];
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 0 ms 332 KB Output is correct
5 Correct 1 ms 460 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 332 KB Output is correct
2 Correct 9 ms 332 KB Output is correct
3 Correct 12 ms 368 KB Output is correct
4 Correct 15 ms 388 KB Output is correct

Subtask #3
70.0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 348 KB Output is correct
2 Correct 0 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 0 ms 332 KB Output is correct
5 Correct 1 ms 460 KB Output is correct
6 Correct 7 ms 332 KB Output is correct
7 Correct 9 ms 332 KB Output is correct
8 Correct 12 ms 368 KB Output is correct
9 Correct 15 ms 388 KB Output is correct
10 Correct 3 ms 332 KB Output is correct
11 Correct 5 ms 332 KB Output is correct
12 Correct 7 ms 356 KB Output is correct
13 Correct 5 ms 332 KB Output is correct
14 Correct 10 ms 380 KB Output is correct
15 Correct 12 ms 368 KB Output is correct
16 Correct 13 ms 456 KB Output is correct
17 Correct 11 ms 372 KB Output is correct
18 Correct 17 ms 384 KB Output is correct