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Submission #19833

# Submission time Handle Problem Language Result Execution time Memory
19833 2016-02-25T06:06:46 Z javelinsman 악수 (kriii4_D) C++14
5 / 100
 4000 ms 9120 KB 
#include<iostream>
#include<cstring>
#include<algorithm>
#include<set>
#include<map>
#include<vector>
using namespace std;

typedef long long ll;

typedef pair<vector<int>,int> state;
map<state,ll> mp;
int n;
const ll MOD = 1e9+7;

ll mm(ll x,ll y){
    x%=MOD;
    if(y==0) return 1;
    if(y==1) return x;
    if(y%2) return mm(x,y-1)*x%MOD;
    ll h = mm(x,y/2);
    return h*h%MOD;
}

ll l_div(ll a,ll b){
    return (a*mm(b,MOD-2))%MOD;
}


ll go(const state& st){
    int trash = st.second;
    const vector<int>& v = st.first;

    if(v.size() == 1) return 0;
    if(mp.count(st)){
        return mp[st];
    }

    int depth = 0;
    for(int x:v){
        depth += x*(x-1)/2;
    }
    depth -= trash;

    int left = n*(n-1)/2 - depth;
    mp[st] = 0;

    for(int i=0;i<v.size();i++){
        for(int j=i+1;j<v.size();j++){
            // combine v[i],v[j]
            vector<int> vv;
            for(int k=0;k<v.size();k++){
                if(k!=i && k!=j) vv.push_back(v[k]);
            }
            vv.push_back(v[i]+v[j]);
            sort(vv.begin(), vv.end());
            state ns = make_pair(vv, trash + v[i]*v[j]-1);

            mp[st] += ((go(ns)+1)%MOD * l_div(v[i]*v[j], left))%MOD;
            mp[st] %= MOD;
        }
    }

    if(trash)
        mp[st] += ((go(make_pair(v, trash-1))+1)%MOD) * l_div(trash, left)%MOD;
    mp[st] %= MOD;

    return mp[st];
}

int main(){
    cin>>n;
    vector<int> v(n,1);
    cout<<go(make_pair(v,0));
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 1728 KB Output is correct
2 Correct 0 ms 1728 KB Output is correct
3 Correct 0 ms 1728 KB Output is correct
4 Correct 0 ms 1728 KB Output is correct
5 Correct 0 ms 1728 KB Output is correct

Subtask #2
0.0 / 95.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 1728 KB Output is correct
2 Correct 0 ms 1728 KB Output is correct
3 Correct 0 ms 1728 KB Output is correct
4 Correct 2 ms 1728 KB Output is correct
5 Correct 0 ms 1728 KB Output is correct
6 Correct 7 ms 1728 KB Output is correct
7 Correct 13 ms 1728 KB Output is correct
8 Correct 24 ms 1860 KB Output is correct
9 Correct 43 ms 1860 KB Output is correct
10 Correct 74 ms 1992 KB Output is correct
11 Correct 121 ms 2124 KB Output is correct
12 Correct 208 ms 2388 KB Output is correct
13 Correct 340 ms 2652 KB Output is correct
14 Correct 543 ms 3180 KB Output is correct
15 Correct 852 ms 3708 KB Output is correct
16 Correct 1328 ms 4500 KB Output is correct
17 Correct 2038 ms 5688 KB Output is correct
18 Correct 3081 ms 7140 KB Output is correct
19 Execution timed out 4000 ms 9120 KB Program timed out
20 Halted 0 ms 0 KB -