Submission #441400

#	Time	Username	Problem	Language	Result	Execution time	Memory
441400		Haruto810198	Paths (BOI18_paths)	C++17	100 / 100	2183 ms	27796 KiB

paths

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define double long double

#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define szof(x) ((int)(x).size())

#define vi vector<int>
#define pii pair<int,int>

#define F first
#define S second

#define pb push_back
#define eb emplace_back
#define mkp make_pair

const int INF = 2147483647;
const int LNF = INF*INF;
const int MOD = 1000000007;
const int mod = 998244353;

//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")

const int MAX = 300010;

int n, m, k;
vi edge[MAX];
int color[MAX];
int cnt[MAX];

vector<vi> per;

void Enum(vi arr){

    if(szof(arr)>=2) per.pb(arr);

    if(szof(arr) == k){
        return;
    }

    FOR(i, 1, k, 1){
        bool flag = 1;
        for(int j : arr){
            if(j==i) flag=0;
        }
        if(flag){
            arr.pb(i);
            Enum(arr);
            arr.pop_back();
        }
    }

}

int solve(vi arr){

    FOR(i, 1, n, 1){
        cnt[i] = (color[i]==arr[0]) ? 1 : 0;
    }

    FOR(i, 1, szof(arr)-1, 1){

        int pc = arr[i-1]; /// previous color
        int cc = arr[i]; /// current color

        FOR(u, 1, n, 1){
            for(int v : edge[u]){
                if(color[u] == pc and color[v] == cc){
                    cnt[v] += cnt[u];
                }
            }
        }

    }

    int ret = 0;
    FOR(i, 1, n, 1){
        if(color[i] == arr.back()){
            ret += cnt[i];
        }
    }

    /*
    cerr<<"solve(";
    for(int i : arr){
        cerr<<i;
    }
    cerr<<") = "<<ret<<endl;
    */

    return ret;

}

signed main(){

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    /// input
    cin>>n>>m>>k;
    FOR(i, 1, n, 1){
        cin>>color[i];
    }
    FOR(i, 1, m, 1){
        int u, v;
        cin>>u>>v;
        edge[u].pb(v);
        edge[v].pb(u);
    }

    /// permutations
    FOR(i, 1, k, 1){
        Enum({i});
    }

    /// solve
    int res = 0;
    for(vi arr : per){
        res += solve(arr);
    }

    cout<<res<<'\n';

    return 0;

}

• Subtask 1: 23 / 23
• Subtask 2: 20 / 20
• Subtask 3: 27 / 27
• Subtask 4: 30 / 30