Submission #983627

#	Time	Username	Problem	Language	Result	Execution time	Memory
983627		dpsaveslives	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	285 ms	36828 KiB

commuter_pass

#include <bits/stdc++.h>
#define f first
#define s second
#define ll long long
using namespace std;
const int MAXN = 1e5+10;
const ll INF = 1e18;
vector<pair<int,ll>> adj[MAXN],adj2[MAXN],readj[MAXN];
int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int N,M; cin >> N >> M;
    int S,T; cin >> S >> T;
    int U,V; cin >> 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});
    }
    vector<ll> DU(N+1,INF); DU[U] = 0;
    priority_queue<pair<ll,int>,vector<pair<ll,int>>,greater<pair<ll,int>>> pq; pq.push({0,U});
    while(!pq.empty()){
        int u = pq.top().s; ll d = pq.top().f; pq.pop();
        if(d != DU[u]) continue;
        for(auto p : adj[u]){
            if(p.s+d < DU[p.f]){
                DU[p.f] = p.s+d;
                pq.push({DU[p.f],p.f});
            }
        }
    }
    vector<ll> DV(N+1,INF); DV[V] = 0; pq.push({0,V});
    while(!pq.empty()){
        int u = pq.top().s; ll d = pq.top().f; pq.pop();
        if(d != DV[u]) continue;
        for(auto p : adj[u]){
            if(p.s+d < DV[p.f]){
                DV[p.f] = p.s+d;
                pq.push({DV[p.f],p.f});
            }
        }
    }
    vector<ll> DS(N+1,INF); DS[S] = 0; pq.push({0,S});
    while(!pq.empty()){
        int u = pq.top().s; ll d = pq.top().f; pq.pop();
        if(d != DS[u]) continue;
        for(auto p : adj[u]){
            if(p.s+d < DS[p.f]){
                DS[p.f] = p.s+d;
                pq.push({DS[p.f],p.f});
            }
        }
    }
    vector<ll> DT(N+1,INF); DT[T] = 0; pq.push({0,T});
    while(!pq.empty()){
        int u = pq.top().s; ll d = pq.top().f; pq.pop();
        if(d != DT[u]) continue;
        for(auto p : adj[u]){
            if(p.s+d < DT[p.f]){
                DT[p.f] = p.s+d;
                pq.push({DT[p.f],p.f});
            }
        }
    }
    vector<int> indeg(N+1,0);
    for(int i = 1;i<=N;++i){
        if(DT[i]+DS[i] != DS[T]) continue;
        for(auto p : adj[i]){
            if(DT[p.f]+DS[p.f] != DS[T]) continue;
            if(DS[i]+p.s == DS[p.f]){
                adj2[i].push_back({p.f,p.s});
                readj[p.f].push_back({i,p.s});
            }
        }
    }
    queue<int> q; q.push(S);
    vector<ll> dp(N+1,INF);
    for(int i = 1;i<=N;++i){
        dp[i] = DU[i];
    }
    ll ans = DU[V];
    vector<ll> cnt(N+1,0);
    while(!q.empty()){
        int u = q.front(); q.pop();
        ans = min(ans,dp[u]+DV[u]);
        for(auto p : adj2[u]){
            dp[p.f] = min(dp[p.f],dp[u]);
            ++cnt[p.f];
            if(cnt[p.f] == readj[p.f].size()){
                q.push(p.f);
            }
        }
    }
    q.push(T);
    dp = vector<ll>(N+1,INF); cnt = vector<ll>(N+1,0);
    for(int i = 1;i<=N;++i){
        dp[i] = DU[i];
    }
    while(!q.empty()){
        int u = q.front(); q.pop();
        ans = min(ans,dp[u]+DV[u]);
        for(auto p : readj[u]){
            dp[p.f] = min(dp[p.f],dp[u]);
            ++cnt[p.f];
            if(cnt[p.f] == adj2[p.f].size()){
                q.push(p.f);
            }
        }
    }
    cout << ans << "\n";
    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:88:25: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'} and 'std::vector<std::pair<int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |             if(cnt[p.f] == readj[p.f].size()){
commuter_pass.cpp:104:25: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type' {aka 'long long int'} and 'std::vector<std::pair<int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  104 |             if(cnt[p.f] == adj2[p.f].size()){

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