Submission #135174

#	Time	Username	Problem	Language	Result	Execution time	Memory
135174		duality	Commuter Pass (JOI18_commuter_pass)	C++11	100 / 100	536 ms	23116 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define mp make_pair
#define pb push_back
typedef long long int LLI;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vpii;

vpii adjList[100000];
LLI distS[100000],distT[100000],distU[100000],distV[100000];
priority_queue<pair<LLI,int> > H;
int findDist(int s,LLI *dist,int N) {
    int i;
    for (i = 0; i < N; i++) dist[i] = -1;
    dist[s] = 0,H.push(mp(0,s));
    while (!H.empty()) {
        int u = H.top().second;
        LLI d = -H.top().first;
        H.pop();

        if (d > dist[u]) continue;
        for (i = 0; i < adjList[u].size(); i++) {
            int v = adjList[u][i].first;
            if ((dist[v] == -1) || (d+adjList[u][i].second < dist[v])) {
                dist[v] = d+adjList[u][i].second;
                H.push(mp(-dist[v],v));
            }
        }
    }
    return 0;
}
LLI dist1[100000],dist2[100000];
int visited[100000];
LLI doDFS(int u,LLI *a,LLI *b,LLI *c) {
    if (visited[u]) return c[u];
    int i;
    visited[u] = 1,c[u] = b[u];
    for (i = 0; i < adjList[u].size(); i++) {
        int v = adjList[u][i].first;
        if (a[u] == a[v]+adjList[u][i].second) c[u] = min(c[u],doDFS(v,a,b,c));
    }
    return c[u];
}
int main() {
    int i;
    int N,M;
    int S,T,U,V;
    int A,B,C;
    scanf("%d %d %d %d %d %d",&N,&M,&S,&T,&U,&V);
    S--,T--,U--,V--;
    for (i = 0; i < M; i++) {
        scanf("%d %d %d",&A,&B,&C);
        A--,B--;
        adjList[A].pb(mp(B,C));
        adjList[B].pb(mp(A,C));
    }

    findDist(S,distS,N),findDist(T,distT,N);
    findDist(U,distU,N),findDist(V,distV,N);
    LLI ans = distU[V];
    for (i = 0; i < N; i++) doDFS(i,distS,distU,dist1);
    fill(visited,visited+N,0);
    for (i = 0; i < N; i++) doDFS(i,distT,distV,dist2);
    for (i = 0; i < N; i++) {
        if (distS[i]+distT[i] == distS[T]) ans = min(ans,dist1[i]+dist2[i]);
    }
    fill(visited,visited+N,0);
    for (i = 0; i < N; i++) doDFS(i,distS,distV,dist1);
    fill(visited,visited+N,0);
    for (i = 0; i < N; i++) doDFS(i,distT,distU,dist2);
    for (i = 0; i < N; i++) {
        if (distS[i]+distT[i] == distS[T]) ans = min(ans,dist1[i]+dist2[i]);
    }
    printf("%lld\n",ans);

    return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int findDist(int, LLI*, int)':
commuter_pass.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (i = 0; i < adjList[u].size(); i++) {
                     ~~^~~~~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'LLI doDFS(int, LLI*, LLI*, LLI*)':
commuter_pass.cpp:39:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i = 0; i < adjList[u].size(); i++) {
                 ~~^~~~~~~~~~~~~~~~~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:50:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d %d %d %d",&N,&M,&S,&T,&U,&V);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:53:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d",&A,&B,&C);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~

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