Submission #683509

#	Time	Username	Problem	Language	Result	Execution time	Memory
683509		yogesh_sane	Commuter Pass (JOI18_commuter_pass)	C++17	0 / 100	2 ms	340 KiB

commuter_pass

#include <iostream>
#include <vector>
#include <queue>
#include <stack>
#include <climits>
using namespace std;
int n, m, s, t, u, v;
vector<vector<int>> parents;
vector<bool> on_sp;
vector<vector<pair<int, int>>> adj;
vector<bool> visited;

void dfs(int s){
    if(visited[s])
        return;
    visited[s] = true;
    on_sp[s] = true;
    for(auto u : parents[s])
        dfs(u);
}
void dijkstras_ST(){
    priority_queue<pair<long long, int>> q;
    vector<long long>dist(n+1,LONG_LONG_MAX);
    q.push({0,s});
    dist[s] = 0;
    while(!q.empty()){
        int node = q.top().second;
        long long dist_node = -q.top().first;
        q.pop();
        if(visited[node])
            continue;
        visited[node] = true;
        for(auto edge : adj[node]){
            int next = edge.first;
            int weight = edge.second;
            if(dist[node] + weight < dist[next]){
                dist[next] = dist[node] + weight;
                parents[next].clear();
                parents[next].push_back(node);
                q.push({-dist[next],next});
            }else if(dist[node] + weight == dist[next]){
                parents[next].push_back(node);
            }
        }
    }
}
void dijkstras_UV(int start, vector<long long> &dist){
    priority_queue<pair<long long, int>> q;
    q.push({0,start});
    dist[start] = 0;
    while(!q.empty()){
        int node = q.top().second;
        long long dist_node = -q.top().first;
        q.pop();
        if(visited[node])
            continue;
        visited[node] = true;
        for(auto edge : adj[node]){
            int next = edge.first;
            int weight = edge.second;
            if(dist[node] + weight < dist[next]){
                dist[next] = dist[node] + weight;
                q.push({-dist[next],next});
            }
        }
    }

}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    freopen("in.txt","r",stdin);
    cin >> n >> m >> s >> t >> u >> v;
    adj = vector<vector<pair<int, int>>>(n+1);
    parents = vector<vector<int>>(n+1);
    on_sp = vector<bool>(n+1);
    visited = vector<bool>(n+1);
    for(int i = 0; i < m; i++){
        int a, b, c;
        cin >> a >> b >> c;
        adj[a].push_back({b,c});
        adj[b].push_back({a,c});
    }
    dijkstras_ST();
    fill(visited.begin(), visited.end(),false);
    dfs(t);
    fill(visited.begin(), visited.end(), false);
    vector<long long> distU(n+1, LONG_LONG_MAX);
    dijkstras_UV(u, distU);
    fill(visited.begin(), visited.end(), false);
    vector<long long> distV(n+1, LONG_LONG_MAX);
    dijkstras_UV(v, distV);
    long long minu = LONG_LONG_MAX, minv = LONG_LONG_MAX;
    for(int i = 1; i <= n; i++)
        if(on_sp[i])
            minu = min(minu, distU[i]);
    for(int i = 1; i <= n; i++)
        if(on_sp[i])
            minv = min(minv, distV[i]);
    long long ans = min(minu+minv,distU[v]);
    cout << ans << '\n';
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'void dijkstras_ST()':
commuter_pass.cpp:28:19: warning: unused variable 'dist_node' [-Wunused-variable]
   28 |         long long dist_node = -q.top().first;
      |                   ^~~~~~~~~
commuter_pass.cpp: In function 'void dijkstras_UV(int, std::vector<long long int>&)':
commuter_pass.cpp:53:19: warning: unused variable 'dist_node' [-Wunused-variable]
   53 |         long long dist_node = -q.top().first;
      |                   ^~~~~~~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:72:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |     freopen("in.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 16
• Subtask 2: 0 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45