Submission #824327

#	Time	Username	Problem	Language	Result	Execution time	Memory
824327		trangtranha28	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	282 ms	41044 KiB

commuter_pass

#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <climits>
#include <vector>
#include <queue>
#include <map>
#include <set>
#define int long long
using namespace std;

const int MAXN = 1e5 + 2;

int n, m;
int s, t, src, tar;

int dis[MAXN] = {0}, dis2[4][MAXN] = {0};
bool vis[MAXN] = {false};

vector <pair <int, int> > adj[MAXN];
vector <int> pp[MAXN], adj2[MAXN], radj[MAXN];

void Dijkstra() {
	// reset:
	memset(dis, 0x3f3f3f3f, sizeof(dis));
	memset(dis2, 0x3f3f3f3f, sizeof(dis2));
	
	// reset:
	dis[s] = 0;
    
    // main:
    priority_queue <pair <int, int>, vector <pair <int, int> >, greater <pair <int, int> > > pq;
    pq.push(make_pair(dis[s], s));
    
    while(pq.empty() == false) {
    	pair <int, int> p = pq.top();
    	pq.pop();
    	
    	int d = p.first;
    	int v = p.second;
				
        if(d != dis[v]) {
        	continue;
		}
		
        for(int i = 0; i < (int)(adj[v].size()); i++) {
        	int u = adj[v][i].first;
        	int w = adj[v][i].second;
        	
            if(dis[u] > dis[v] + w) {
            	dis[u] = dis[v] + w;
                pq.push(make_pair(dis[u], u));
                pp[u] = {v};
            } else if(dis[u] == dis[v] + w) {
            	pp[u].push_back(v);
			}
        }
    }
    return;
}

void Dijkstra2() {
	// reset:
	dis2[0][src] = 0;
    
    // main:
    priority_queue <pair <int, pair <int, int> >, vector <pair <int, pair <int, int> > >, greater <pair <int, pair <int, int> > > > pq2;
	pq2.push(make_pair(dis2[0][src], make_pair(0, src)));
    
    while(pq2.empty() == false) {
    	pair <int, pair <int, int> > p2 = pq2.top();
    	pq2.pop();
    	
    	int d = p2.first;
    	int i = p2.second.first;
    	int v = p2.second.second;
    	
    	// output:
        if(v == tar) {
        	cout << d << "\n";
			return;
		}
		
        if(d != dis2[i][v]) {
        	continue;
		}
		
        for(int j = 0; j < (int)(adj[v].size()); j++) {
        	int u = adj[v][j].first;
        	int w = adj[v][j].second;
        	
        	int ni = 0;
        	if(i != 0) {
        		ni = 3;
			}

            if(dis2[ni][u] > dis2[i][v] + w) {
            	dis2[ni][u] = dis2[i][v] + w;
                pq2.push(make_pair(dis2[ni][u], make_pair(ni, u)));
            }
        }
        
        if(i == 0 || i == 1) {
            for(int j = 0; j < (int)(adj2[v].size()); j++) {
            	int u = adj2[v][j];
                if(dis2[1][u] > dis2[i][v]) {
                	dis2[1][u] = dis2[i][v];
                    pq2.push(make_pair(dis2[1][u], make_pair(1, u)));
                }
            }
        }
        
        if(i == 0 || i == 2) {
            for(int j = 0; j < (int)(radj[v].size()); j++) {
            	int u = radj[v][j];
                if(dis2[2][u] > dis2[i][v]) {
                	dis2[2][u] = dis2[i][v];
                    pq2.push(make_pair(dis2[2][u], make_pair(2, u)));
                }
            }
        }
    }
    return;
}

void programme() {
	// input:
    cin >> n >> m >> s >> t >> src >> tar;
    
    for(int i = 1; i <= m; i++) {
        int a, b, w;
		cin >> a >> b >> w;
        adj[a].push_back(make_pair(b, w));
        adj[b].push_back(make_pair(a, w));
    }
    
    // solve:
	Dijkstra();
    
    queue <int> q;
	q.push(t);
	
	vis[t] = true;
	
    while(q.empty() == false) {
        int v = q.front();
		q.pop();
		
        for(int i = 0; i < (int)(pp[v].size()); i++) {
        	int u = pp[v][i];
            adj2[v].push_back(u);
            radj[u].push_back(v);
            
            if(vis[u] == false) {
            	vis[u] = true;
				q.push(u);
			}
        }
    }
    
    // output:
    Dijkstra2();
    return;
}

signed main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	
//	freopen("_mint.inp", "r", stdin);
//	freopen("_mint.out", "w", stdout);
	
	programme();
    return 0;
}

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 45 / 45