Submission #642698

#	Time	Username	Problem	Language	Result	Execution time	Memory
642698		andreast12	Paths (BOI18_paths)	C++17	100 / 100	423 ms	24820 KiB

paths

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pb push_back
const int mod=1e9+7, maxn=3e5+5;
int n, m, k, c[maxn], u, v, tmp, order[125][10], p[10], NEXT[10], now;
vector<int> adj[maxn];
bool vis[10];
ll byk[maxn], tot[10], ans;
queue<int> q;
string s;
map<string, bool> pernah;

void perm(int idx) {
	if(idx>k) {
		tmp++;
		for(int i=1; i<=k; i++) order[tmp][i]=p[i];
		return;
	}
	for(int i=1; i<=k; i++) {
		if(!vis[i]) {
			vis[i]=true;
			p[idx]=i;
			perm(idx+1);
			vis[i]=false;
		}
	}
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	cin >> n >> m >> k;
	for(int i=1; i<=n; i++) cin >> c[i];
	while(m--) {
		cin >> u >> v;
		adj[u].pb(v);
		adj[v].pb(u);
	}
	perm(1);
	for(int i=1; i<=tmp; i++) {
		for(int j=1; j<=k; j++) NEXT[order[i][j]]=order[i][j+1], tot[j]=0; 
		for(int j=1; j<=n; j++) {
			if(c[j]==order[i][1]) {
				q.push(j);
				byk[j]=1;
			} else byk[j]=-1;
		}
		while(!q.empty()) {
			now=q.front();
			tot[c[now]]+=byk[now];
			q.pop();
			for(auto nxt:adj[now]) {
				if(c[nxt]==NEXT[c[now]]) {
					if(byk[nxt]==-1) {
						byk[nxt]=byk[now];
						q.push(nxt);
					} else byk[nxt]+=byk[now];
				}		
			}
		}
		s=order[i][1]-'0';
		for(int j=2; j<=k; j++) {
			s+=order[i][j]-'0';
			if(!pernah[s]) {
				ans+=tot[order[i][j]];
				pernah[s]=true;
			}
		}
	}
	cout << ans << '\n';
}

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