Submission #1254198

#	Time	Username	Problem	Language	Result	Execution time	Memory
1254198		rcll	Commuter Pass (JOI18_commuter_pass)	C++20	100 / 100	326 ms	27380 KiB

commuter_pass

#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

vector<pair<ll,ll>> graph[100001];
ll du[100001],dv[100001],ds[100001],dp[2][100001],ans;
bool visited[100001];

void dijkstra1(ll start,ll arr[]) {
    fill(visited,visited+100001,false);
    priority_queue<pair<ll,ll>> pq;
    pq.push({0,start});
    while (!pq.empty()) {
        ll c,node;
        tie(c,node)=pq.top();
        pq.pop();
        if (!visited[node]) {
            arr[node]=-c;
            visited[node]=true;
            for (auto &i : graph[node]) pq.push({c-i.second,i.first});
        }
    }
}

void dijkstra2(ll start,ll end) {
    fill(dp[0],dp[0]+100001,LLONG_MAX / 2);
    fill(dp[1],dp[1]+100001,LLONG_MAX / 2);
    fill(visited,visited+100001,false);
    priority_queue<pair<ll,pair<ll,ll>>> pq;
    pq.push({0,{start,0}});
    dp[0][0]=dp[1][0]=LLONG_MAX / 2;
    while (!pq.empty()) {
        ll c,node,par;
        pair<ll,ll> p;
        tie(c,p)=pq.top();
        tie(node,par)=p;
        pq.pop();
        if (!visited[node]) {
            visited[node]=true;
            ds[node]=-c;
            dp[0][node]=min(du[node],dp[0][par]);
            dp[1][node]=min(dv[node],dp[1][par]);
            for (auto i : graph[node]) pq.push({c-i.second,{i.first,node}});
        } else if (-c==ds[node]) {
            if (min(du[node],dp[0][par])+min(dv[node],dp[1][par]) <=
                dp[0][node]+dp[1][node]) {
                dp[0][node]=min(du[node],dp[0][par]);
                dp[1][node]=min(dv[node],dp[1][par]);
            }
        }
    }
    ans=min(ans,dp[0][end]+dp[1][end]);
}

int main() {
    iostream::sync_with_stdio(false);
    cin.tie(0);
    ll n,m,s,t,u,v;
    cin >> n >> m >> s >> t >> u >> v;
    for (int i=0; i < m; i++) {
        ll a,b,c;
        cin >> a >> b >> c;
        graph[a].push_back({b,c});
        graph[b].push_back({a,c});
    }
    dijkstra1(u,du);
    dijkstra1(v,dv);
    ans=du[v];
    dijkstra2(s,t);
    dijkstra2(t,s);
    cout << ans << '\n';
    return 0;
}

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