oj.uz

Submission #224107

# Submission time Handle Problem Language Result Execution time Memory
224107 2020-04-17T08:09:37 Z errorgorn Olympic Bus (JOI20_ho_t4) C++14
5 / 100
 1000 ms 7012 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl;

#define rep(x,start,end) for(auto x=start-(start>end);x!=end-(start>end);x+=(start<end?1:-1))
#define all(x) x.begin(),x.end()

ll MAX(ll a){return a;}
ll MIN(ll a){return a;}
template<typename... Args>
ll MAX(ll a, Args... args) { return max(a,MAX(args...)); }
template<typename... Args>
ll MIN(ll a, Args... args) { return min(a,MIN(args...)); }

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>

const ll INF=1e18;

struct E{
	int u,v;
	ll len,flip;
	int id;

	E(int a,int b,int c,int d,int e){
		u=a,v=b;
		len=c,flip=d;
		id=e;
	}
};

int n,m;
vector<E> al[205];
vector<E> al_rev[205]; //store reversed edges
vector<E> edges;

priority_queue<ii,vector<ii>,greater<ii> > pq;
ll sf[205]; //source front
ll sb[205]; //source back
ll tf[205]; //sink front
ll tb[205]; //sink back

ll w1[205];
ll w2[205];

bool path[50005]; //is some edge in SP

ll temp,node; //stuff for dijk

void initial_d(){ //epic name
	rep(x,0,205) sf[x]=sb[x]=tf[x]=tb[x]=INF;
	
	sf[1]=0;
	pq.push(ii(sf[1],1));
	while (!pq.empty()){
		temp=pq.top().first;
		node=pq.top().second;
		pq.pop();
		if (temp>sf[node]) continue; //important
		for (auto &it:al[node]){
			if (sf[it.v]>sf[node]+it.len){
				sf[it.v]=sf[node]+it.len;
				pq.push(ii (sf[it.v],it.v));
			}
		}
	} 
	
	sb[1]=0;
	pq.push(ii(sb[1],1));
	while (!pq.empty()){
		temp=pq.top().first;
		node=pq.top().second;
		pq.pop();
		if (temp>sb[node]) continue; //important
		for (auto &it:al_rev[node]){
			if (sb[it.v]>sb[node]+it.len){
				sb[it.v]=sb[node]+it.len;
				pq.push(ii (sb[it.v],it.v));
			}
		}
	} 
	
	tf[n]=0;
	pq.push(ii(tf[n],n));
	while (!pq.empty()){
		temp=pq.top().first;
		node=pq.top().second;
		pq.pop();
		if (temp>tf[node]) continue; //important
		for (auto &it:al[node]){
			if (tf[it.v]>tf[node]+it.len){
				tf[it.v]=tf[node]+it.len;
				pq.push(ii (tf[it.v],it.v));
			}
		}
	} 
	
	tb[n]=0;
	pq.push(ii(tb[n],n));
	while (!pq.empty()){
		temp=pq.top().first;
		node=pq.top().second;
		pq.pop();
		if (temp>tb[node]) continue; //important
		for (auto &it:al_rev[node]){
			if (tb[it.v]>tb[node]+it.len){
				tb[it.v]=tb[node]+it.len;
				pq.push(ii (tb[it.v],it.v));
			}
		}
	}
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	cin>>n>>m;
	
	int a,b,c,d;
	rep(x,0,m){
		cin>>a>>b>>c>>d;
		
		al[a].push_back(E(a,b,c,d,x));
		al_rev[b].push_back(E(b,a,c,d,x));
		edges.push_back(E(a,b,c,d,x));
	}
	
	initial_d();
	
	//try dijk start and end
	ll ans=sf[n]+tf[1];
	
	if (m>1000){
		for (auto &it:edges){
			ans=min(ans,min(sf[n],sf[it.v]+it.len+tb[it.u])+min(tf[1],tf[it.v]+it.len+sb[it.u])+it.flip);
		}
		
		cout<<ans<<endl;
	}
	
	/*
	rep(x,1,n+1){
		cout<<sf[x]<<" "<<sb[x]<<" "<<tf[x]<<" "<<tb[x]<<endl;
	}
	*/
	
	rep(bad,0,m){
		//we run a new iteration of dijkstra for this where we flip every edge on the SP
		//cout<<edges[bad].u<<" "<<edges[bad].v<<endl;
		
		al[edges[bad].v].push_back(E(-1,edges[bad].u,edges[bad].len,-1,-1));
		
		rep(x,0,205) w1[x]=w2[x]=INF;
		
		w1[1]=0;
		pq.push(ii(w1[1],1));
		while (!pq.empty()){
			temp=pq.top().first;
			node=pq.top().second;
			pq.pop();
			if (temp>w1[node]) continue; //important
			for (auto &it:al[node]){
				if (it.id==edges[bad].id) continue;
				if (w1[it.v]>w1[node]+it.len){
					w1[it.v]=w1[node]+it.len;
					pq.push(ii (w1[it.v],it.v));
				}
			}
		}
		
		w2[n]=0;
		pq.push(ii(w2[n],n));
		while (!pq.empty()){
			temp=pq.top().first;
			node=pq.top().second;
			pq.pop();
			if (temp>w2[node]) continue; //important
			for (auto &it:al[node]){
				if (it.id==edges[bad].id) continue;
				if (w2[it.v]>w2[node]+it.len){
					w2[it.v]=w2[node]+it.len;
					pq.push(ii (w2[it.v],it.v));
				}
			}
		}
		
		ans=min(ans,w1[n]+w2[1]+edges[bad].flip);
		al[edges[bad].v].pop_back();
	}
	
	if (ans>=INF) cout<<-1<<endl;
	else cout<<ans<<endl;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 512 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 53 ms 512 KB Output is correct
4 Correct 60 ms 632 KB Output is correct
5 Correct 18 ms 512 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 4 ms 384 KB Output is correct
8 Correct 4 ms 384 KB Output is correct
9 Correct 8 ms 512 KB Output is correct
10 Correct 85 ms 512 KB Output is correct
11 Correct 80 ms 512 KB Output is correct
12 Correct 79 ms 512 KB Output is correct
13 Correct 28 ms 512 KB Output is correct
14 Correct 37 ms 512 KB Output is correct
15 Correct 33 ms 512 KB Output is correct
16 Correct 37 ms 632 KB Output is correct

Subtask #2
0 / 11.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1094 ms 7012 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #3
0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 632 KB Output is correct
2 Correct 6 ms 384 KB Output is correct
3 Execution timed out 1095 ms 5876 KB Time limit exceeded
4 Halted 0 ms 0 KB -

Subtask #4
0 / 63.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 512 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 53 ms 512 KB Output is correct
4 Correct 60 ms 632 KB Output is correct
5 Correct 18 ms 512 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Correct 4 ms 384 KB Output is correct
8 Correct 4 ms 384 KB Output is correct
9 Correct 8 ms 512 KB Output is correct
10 Correct 85 ms 512 KB Output is correct
11 Correct 80 ms 512 KB Output is correct
12 Correct 79 ms 512 KB Output is correct
13 Correct 28 ms 512 KB Output is correct
14 Correct 37 ms 512 KB Output is correct
15 Correct 33 ms 512 KB Output is correct
16 Correct 37 ms 632 KB Output is correct
17 Execution timed out 1094 ms 7012 KB Time limit exceeded
18 Halted 0 ms 0 KB -