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Submission #417323

# Submission time Handle Problem Language Result Execution time Memory
417323 2021-06-03T14:50:03 Z AmineWeslati Olympic Bus (JOI20_ho_t4) C++14
5 / 100
 67 ms 3820 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<int>vi; 
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) begin(x),end(x)

typedef pair<int,int>pi;
#define fi first
#define se second

#define FOR(i,a,b) for(int i=a; i<b; i++)
#define ROF(i,a,b) for(int i=b-1; i>=a; i--)

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

void ckmin(int &x, int y){x=min(x,y);}

const int INF=1e9+100;
const int MX=5e4+10;

int N,M,U[MX],V[MX],W[MX],C[MX];

vector<pair<pi,int>>adj[MX];
void build(){
	FOR(i,1,N+1) adj[i].clear();
	FOR(i,0,M){
		int u=U[i],v=V[i],w=W[i];
		adj[u].pb({{v,w},i});
	}
}

int dist[MX],par[MX],par_idx[MX];
int fu,fv; 
void dijkstra(int s){
	FOR(i,1,N+1) dist[i]=INF;
	dist[s]=0;

	priority_queue<pi,vector<pi>,greater<pi>>q;
	q.push({0,s});

	while(sz(q)){
		int u=q.top().se,d=q.top().fi;
		q.pop();

		if(d>dist[u]) continue;

		for(auto it: adj[u]){
			int v=it.fi.fi,w=it.fi.se,idx=it.se; 
			if(!(fu==u && fv==v) && dist[v]>d+w){
				dist[v]=d+w; 
				par[v]=u; 
				par_idx[v]=idx;
				q.push({dist[v],v});
			}
		}
	}
}

vi chosen(MX,0);
int to1[MX],toN[MX],from1[MX],fromN[MX];
void precompute(){
	build();

	dijkstra(1);
	FOR(i,1,N+1) from1[i]=dist[i];

	int u=N; 
	while(dist[N]!=INF && u!=1){
		chosen[par_idx[u]]=1;
		u=par[u];
	}

	dijkstra(N);
	FOR(i,1,N+1) fromN[i]=dist[i];

	u=1;
	while(dist[1]!=INF && u!=N){
		chosen[par_idx[u]]=1;
		u=par[u];
	}
	

	FOR(i,0,M) swap(U[i],V[i]);
	build();
	FOR(i,0,M) swap(U[i],V[i]);

	dijkstra(1);
	FOR(i,1,N+1) to1[i]=dist[i];

	dijkstra(N);
	FOR(i,1,N+1) toN[i]=dist[i];
}

int main(){
	IO();

	cin>>N>>M;
	FOR(i,0,M) cin>>U[i]>>V[i]>>W[i]>>C[i];

	precompute();

	int ans=2e9;
	if(toN[1]!=INF && to1[N]!=INF) ans=toN[1]+to1[N]; 

	build();
	FOR(i,0,M){
		if(chosen[i]){
			adj[V[i]].pb({{U[i],W[i]},i});
			fu=U[i],fv=V[i];

			bool yes=1;

			int x=C[i];
			dijkstra(1);
			x+=dist[N];
			yes&=dist[N]!=INF; 
			dijkstra(N);
			x+=dist[1];
			yes&=dist[1]!=INF; 
			if(yes) ckmin(ans,x);

			adj[V[i]].pop_back();
			fu=-1; fv=-1;
		}
		else{
			int u=U[i],v=V[i];
			swap(u,v);

			bool c1=(max(max(from1[u],toN[v]),fromN[1])!=INF),
			c2=(max(max(from1[N],to1[v]),fromN[u])!=INF),
			c3=(max(max(from1[u],toN[v]),max(fromN[u],to1[v]))!=INF);

			if(c1)
			ckmin(ans,from1[u]+W[i]+C[i]+toN[v]+fromN[1]);
			if(c2)
			ckmin(ans,from1[N]+fromN[u]+C[i]+W[i]+to1[v]);
			if(c3)
			ckmin(ans,from1[u]+W[i]+C[i]+toN[v]+fromN[u]+W[i]+to1[v]);
		}
	}

	if(ans>=2e9) ans=-1;
	cout << ans << endl;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1740 KB Output is correct
2 Correct 1 ms 1740 KB Output is correct
3 Correct 3 ms 1740 KB Output is correct
4 Correct 3 ms 1740 KB Output is correct
5 Correct 2 ms 1740 KB Output is correct
6 Correct 1 ms 1740 KB Output is correct
7 Correct 1 ms 1612 KB Output is correct
8 Correct 1 ms 1612 KB Output is correct
9 Correct 2 ms 1700 KB Output is correct
10 Correct 20 ms 1776 KB Output is correct
11 Correct 25 ms 1776 KB Output is correct
12 Correct 24 ms 1780 KB Output is correct
13 Correct 3 ms 1740 KB Output is correct
14 Correct 3 ms 1740 KB Output is correct
15 Correct 3 ms 1740 KB Output is correct
16 Correct 3 ms 1740 KB Output is correct

Subtask #2
0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 64 ms 3668 KB Output is correct
2 Correct 62 ms 3580 KB Output is correct
3 Correct 67 ms 3656 KB Output is correct
4 Correct 4 ms 1740 KB Output is correct
5 Correct 4 ms 1740 KB Output is correct
6 Correct 2 ms 1740 KB Output is correct
7 Correct 2 ms 1740 KB Output is correct
8 Incorrect 2 ms 1612 KB Output isn't correct
9 Halted 0 ms 0 KB -

Subtask #3
0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1740 KB Output is correct
2 Correct 2 ms 1740 KB Output is correct
3 Correct 48 ms 3008 KB Output is correct
4 Correct 2 ms 1740 KB Output is correct
5 Correct 60 ms 3584 KB Output is correct
6 Correct 1 ms 1612 KB Output is correct
7 Correct 1 ms 1612 KB Output is correct
8 Correct 59 ms 3820 KB Output is correct
9 Correct 58 ms 3776 KB Output is correct
10 Correct 59 ms 3524 KB Output is correct
11 Correct 63 ms 3528 KB Output is correct
12 Correct 59 ms 3524 KB Output is correct
13 Incorrect 1 ms 1612 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #4
0 / 63.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 1740 KB Output is correct
2 Correct 1 ms 1740 KB Output is correct
3 Correct 3 ms 1740 KB Output is correct
4 Correct 3 ms 1740 KB Output is correct
5 Correct 2 ms 1740 KB Output is correct
6 Correct 1 ms 1740 KB Output is correct
7 Correct 1 ms 1612 KB Output is correct
8 Correct 1 ms 1612 KB Output is correct
9 Correct 2 ms 1700 KB Output is correct
10 Correct 20 ms 1776 KB Output is correct
11 Correct 25 ms 1776 KB Output is correct
12 Correct 24 ms 1780 KB Output is correct
13 Correct 3 ms 1740 KB Output is correct
14 Correct 3 ms 1740 KB Output is correct
15 Correct 3 ms 1740 KB Output is correct
16 Correct 3 ms 1740 KB Output is correct
17 Correct 64 ms 3668 KB Output is correct
18 Correct 62 ms 3580 KB Output is correct
19 Correct 67 ms 3656 KB Output is correct
20 Correct 4 ms 1740 KB Output is correct
21 Correct 4 ms 1740 KB Output is correct
22 Correct 2 ms 1740 KB Output is correct
23 Correct 2 ms 1740 KB Output is correct
24 Incorrect 2 ms 1612 KB Output isn't correct
25 Halted 0 ms 0 KB -