Submission #237896

#	Time	Username	Problem	Language	Result	Execution time	Memory
237896		aggu_01000101	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	590 ms	26684 KiB

commuter_pass

#include <bits/stdc++.h>
#define int long long
#define INF 1000000000000000000
#define lchild(i) (i*2 + 1)
#define rchild(i) (i*2 + 2)
#define mid(l, u) ((l+u)/2)
#define MOD 1000000007
using namespace std;
int n, m, s, t, u, v, sp;
vector<pair<int, int>> adj[100005];
vector<int> opte[100005];
bool visited[100005];
int dp[100005];
int ans;
void dij(int start, int arr[]){
    for(int i = 1;i<=n;i++) arr[i] = INF;
    arr[start] = 0;
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    pq.push({0, start});
    while(!pq.empty()){
        pair<int, int> curr = pq.top();
        pq.pop();
        if(curr.first != arr[curr.second]) continue;
        for(pair<int, int> j: adj[curr.second]){
            if((j.second + curr.first)>=arr[j.first]) continue;
            arr[j.first] = j.second + curr.first;
            pq.push({arr[j.first], j.first});
        }
    }
}
void dfs(int x){
    if(visited[x]) return;
    visited[x] = true;
    for(int j: opte[x]){
        dfs(j);
        dp[x] = min(dp[x], dp[j]);
    }
}
int findans(int a1[], int a2[]){
    for(int i = 1;i<=n;i++){
        visited[i] = false;
        dp[i] = a2[i];
    }
    for(int i = 1;i<=n;i++){
        dfs(i);
    }
    for(int i = 1;i<=n;i++){
        ans = min(ans, dp[i] + a1[i]);
    }
    return ans;
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>m>>s>>t>>u>>v;
    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});
    }
    int sd[n+1], td[n+1], ud[n+1], vd[n+1];
    dij(s, sd);
    dij(t, td);
    dij(u, ud);
    dij(v, vd);
    sp = sd[t];
    ans = ud[v];
    for(int i = 1;i<=n;i++){
        for(pair<int, int> j: adj[i]){
            if (sd[i] + j.second + td[j.first] == sp){
                opte[i].push_back(j.first);
            }
        }
    }
    findans(ud, vd);
    findans(vd, ud);
    cout<<ans<<"\n";
    return 0;
}

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