oj.uz

Submission #224767

# Submission time Handle Problem Language Result Execution time Memory
224767 2020-04-18T18:40:06 Z errorgorn Olympic Bus (JOI20_ho_t4) C++14
11 / 100
 36 ms 7528 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
int ps[205]; //parent front
ll sb[205]; //source back
int pt[205]; //parent back
ll tf[205]; //sink front
ll tb[205]; //sink back

ll w[205];

map<int,ll> sp_f,sp_b; //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;
				ps[it.v]=it.id;
				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;
				pt[it.v]=it.id;
				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));
			}
		}
	}
}

void SP_d(){
	if (sf[n]!=INF){ //find best from S to T
		int curr=n;
		
		while (curr!=1){
			//debug(ps[curr]);
			sp_f[ps[curr]]=INF;
			curr=edges[ps[curr]].u;
		}
		
		for (auto &it2:sp_f){
			//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;
			rep(x,0,205) w[x]=INF;
			
			w[1]=0;
			pq.push(ii(w[1],1));
			while (!pq.empty()){
				temp=pq.top().first;
				node=pq.top().second;
				pq.pop();
				if (temp>w[node]) continue; //important
				for (auto &it:al[node]){
					if (it.id==it2.first) continue;
					if (w[it.v]>w[node]+it.len){
						w[it.v]=w[node]+it.len;
						pq.push(ii (w[it.v],it.v));
					}
				}
			}
			it2.second=w[n];
		}
	}
	
	//find the path on best line from T->S
	if (tf[1]!=INF){
		int curr=1;
		
		while (curr!=n){
			//debug(pt[curr]);
			sp_b[pt[curr]]=INF;
			curr=edges[pt[curr]].u;
		}
		
		for (auto &it2:sp_b) {
			//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;
			
			rep(x,0,205) w[x]=INF;
			
			w[n]=0;
			pq.push(ii(w[n],n));
			while (!pq.empty()){
				temp=pq.top().first;
				node=pq.top().second;
				pq.pop();
				if (temp>w[node]) continue; //important
				for (auto &it:al[node]){
					if (it.id==it2.first) continue;
					if (w[it.v]>w[node]+it.len){
						w[it.v]=w[node]+it.len;
						pq.push(ii (w[it.v],it.v));
					}
				}
			}

			it2.second=w[1];
		}
	}
}

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();
	
	SP_d();
	
	//try dijk start and end
	ll ans=sf[n]+tf[1];
	
	for (auto &it:edges){
		ans=min(ans,min((sp_f.count(it.id)?sp_f[it.id]:sf[n]),sf[it.v]+tb[it.u]+it.len)+min((sp_b.count(it.id)?sp_b[it.id]:tf[1]),tf[it.v]+sb[it.u]+it.len)+it.flip);
		//debug(min((sp_f.count(it.id)?sp_f[it.id]:sf[n]),sf[it.v]+tb[it.u]+it.len));
		//debug(min((sp_b.count(it.id)?sp_b[it.id]:tf[1]),tf[it.v]+sb[it.u]+it.len));
	}
	
	if (ans>=INF) cout<<-1<<endl;
	else cout<<ans<<endl;
}

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 512 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 6 ms 512 KB Output is correct
4 Correct 6 ms 512 KB Output is correct
5 Correct 5 ms 512 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Incorrect 5 ms 384 KB Output isn't correct
8 Halted 0 ms 0 KB -

Subtask #2
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 34 ms 6888 KB Output is correct
2 Correct 35 ms 6888 KB Output is correct
3 Correct 35 ms 6768 KB Output is correct
4 Correct 6 ms 640 KB Output is correct
5 Correct 5 ms 512 KB Output is correct
6 Correct 5 ms 512 KB Output is correct
7 Correct 5 ms 384 KB Output is correct
8 Correct 4 ms 384 KB Output is correct
9 Correct 34 ms 6888 KB Output is correct
10 Correct 35 ms 6888 KB Output is correct
11 Correct 35 ms 6628 KB Output is correct
12 Correct 34 ms 6768 KB Output is correct
13 Correct 34 ms 6632 KB Output is correct
14 Correct 36 ms 7400 KB Output is correct

Subtask #3
0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 512 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 25 ms 6644 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 32 ms 7528 KB Output is correct
6 Incorrect 5 ms 384 KB Output isn't correct
7 Halted 0 ms 0 KB -

Subtask #4
0 / 63.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 512 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 6 ms 512 KB Output is correct
4 Correct 6 ms 512 KB Output is correct
5 Correct 5 ms 512 KB Output is correct
6 Correct 5 ms 384 KB Output is correct
7 Incorrect 5 ms 384 KB Output isn't correct
8 Halted 0 ms 0 KB -