Submission #1192432

#	Time	Username	Problem	Language	Result	Execution time	Memory
1192432		julia_08	Paths (BOI18_paths)	C++20	100 / 100	842 ms	26432 KiB

paths

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

const int MAXN = 3e5 + 10;

int color[MAXN];

vector<int> adj[MAXN];

ll dp[5][MAXN];

int n, m;

ll solve(vector<int> c){

  ll r = 0;

  int K = (int) c.size();

  do{

    for(int k=0; k<K; k++){
      for(int i=1; i<=n; i++){
        dp[k][i] = 0;
        if(k == K - 1 && color[i] == c[k]) dp[k][i] = 1;
      }
    }

    for(int k=K-2; k>=0; k--){
      for(int i=1; i<=n; i++){

        if(color[i] == c[k]){
          for(auto j : adj[i]){
            if(color[j] == c[k + 1]){
              dp[k][i] += dp[k + 1][j];
            }
          }
        }

        if(k == 0) r += dp[k][i];

      }
    }

  } while(next_permutation(c.begin(), c.end()));

  return r;
}

int main(){
  cin.tie(0)->sync_with_stdio(0);

  int k; cin >> n >> m >> k;

  for(int i=1; i<=n; i++) cin >> color[i];

  for(int i=1; i<=m; i++){
    int a, b; cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }

  ll ans = 0;

  for(int a=1; a<=k; a++){
    for(int b=a+1; b<=k; b++){
      ans += solve({a, b});
      for(int c=b+1; c<=k; c++){
        ans += solve({a, b, c});
        for(int d=c+1; d<=k; d++){
          ans += solve({a, b, c, d});
          for(int e=d+1; e<=k; e++){
            ans += solve({a, b, c, d, e});
          }
        }
      }
    }
  }

  cout << ans << "\n";

  return 0;
}

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