제출 #683528

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
683528		yogesh_sane	Commuter Pass (JOI18_commuter_pass)	C++17	15 / 100	2070 ms	19416 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<vector<pair<int, int>>> adj;
vector<bool> visited;
vector<long long> distU, distV;
vector<int> sp;

long long ans = LONG_LONG_MAX;
void find_ans(){
    vector<bool> on_sp(n+1);
    for(int j = 0; j < sp.size(); j++)
        on_sp[sp[j]] = true;
    long long minu = LONG_LONG_MAX/2, minv = LONG_LONG_MAX/2;
    for(int k = 1; k <= n; k++)
        if(on_sp[k])
            minu = min(minu, distU[k]);
    for(int k = 1; k <= n; k++)
        if(on_sp[k])
            minv = min(minv, distV[k]);
    ans = min(ans, minu+minv);    
}


void dfs(int node){
    sp.push_back(node);
    if(node == s){
        find_ans();
    }
    for(auto gp : parents[node])
        dfs(gp);
    sp.pop_back();
}
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);
    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);
    fill(visited.begin(), visited.end(), false);
    distU = vector<long long>(n+1, LONG_LONG_MAX);
    dijkstras_UV(u, distU);
    fill(visited.begin(), visited.end(), false);
    distV = vector<long long>(n+1, LONG_LONG_MAX);
    dijkstras_UV(v, distV);
    dfs(t);   
    ans = min(ans,distU[v]);
    cout << ans << '\n';
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

commuter_pass.cpp: In function 'void find_ans()':
commuter_pass.cpp:17:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |     for(int j = 0; j < sp.size(); j++)
      |                    ~~^~~~~~~~~~~
commuter_pass.cpp: In function 'void dijkstras_ST()':
commuter_pass.cpp:46:19: warning: unused variable 'dist_node' [-Wunused-variable]
   46 |         long long dist_node = -q.top().first;
      |                   ^~~~~~~~~
commuter_pass.cpp: In function 'void dijkstras_UV(int, std::vector<long long int>&)':
commuter_pass.cpp:71:19: warning: unused variable 'dist_node' [-Wunused-variable]
   71 |         long long dist_node = -q.top().first;
      |                   ^~~~~~~~~

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