Submission #400392

#	Time	Username	Problem	Language	Result	Execution time	Memory
400392		AmineWeslati	Robot (JOI21_ho_t4)	C++14	0 / 100	156 ms	8424 KiB

Main

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

typedef long long ll;
typedef vector<int> vi;
#define pb push_back
#define sz(v) (int)v.size()
typedef pair<int,int> pi;
#define fi first 
#define se second

#define FOR(i,a,b) for(int i=a; i<b; i++)



void IO(){
#ifdef LOCAL
	freopen("input.txt","r",stdin);
	freopen("output.txt","w",stdout);
#endif
}
//------------------------------------------------------//

bool ckmin(ll &x, ll y){
	if(x<=y) return 0;
	x=y; return 1; 
}

struct state{
	int v,c,w; 
};

const int MX=1e3+10;
const ll INF=1e18;
int N,M;
vector<state> adj[MX];

int main(){
	IO();

	cin>>N>>M;
	FOR(i,0,M){
		int u,v,c,w; cin>>u>>v>>c>>w; u--; v--;
		adj[u].pb(state{v,c,w});
		adj[v].pb(state{u,c,w});
	}

	//precompting can

	map<int,int>can[N]; 
	FOR(u,0,N){
		unordered_map<int,int>mp;
		for(auto nxt: adj[u]){
			mp[nxt.c]++;
		}

		int nb=0,color=-1;
		FOR(i,1,M+1) if(!mp.count(i)) color=i,nb++;

		for(auto nxt: adj[u]){
			int v=nxt.v,c=nxt.c,w=nxt.w;
				
			int cur_color=color;
			if(mp[c]==1){
				nb++;	
				cur_color=c;
			}

			if(nb>1) can[u][v]=-1;
			else can[u][v]=cur_color;

			
			if(mp[c]==1) nb--;
		}	
	}

	//end


	ll dist[N][N]; FOR(i,0,N) FOR(j,0,N) dist[i][j]=INF; 
	dist[0][0]=0;
	priority_queue<pair<ll,pi>,vector<pair<ll,pi>>,greater<pair<ll,pi>>> q;
	q.push({0,{0,0}});

	while(sz(q)){
		pair<ll,pi>cur=q.top();
		q.pop();
		int u=cur.se.fi,p=cur.se.se; ll d=cur.fi;
		if(d>dist[u][p]) continue;

		unordered_map<int,int>mp;
		for(auto nxt: adj[u]) if(nxt.v!=p){
			mp[nxt.c]++;
		}
		for(auto nxt: adj[u]) if(nxt.v!=p){
			int v=nxt.v,c=nxt.c,w=nxt.w;
			if(mp[c]>1 || (u!=p && can[p][u]==c)){
				if(ckmin(dist[v][u],d+w)) q.push({d+w,{v,u}});
			}
			else{
				if(ckmin(dist[v][u],d)) q.push({d,{v,u}});
			}
		}
	}

	ll ans=INF; 
	FOR(i,0,N) ckmin(ans,dist[N-1][i]);

	if(ans==INF) ans=-1;
	cout << ans << endl;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:61:24: warning: unused variable 'w' [-Wunused-variable]
   61 |    int v=nxt.v,c=nxt.c,w=nxt.w;
      |                        ^

• Subtask 1: 0 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42