Submission #853303

#	Time	Username	Problem	Language	Result	Execution time	Memory
853303		Zero_OP	Commuter Pass (JOI18_commuter_pass)	C++14	24 / 100	202 ms	22284 KiB

commuter_pass

#include<bits/stdc++.h>

using namespace std;

#define range(v) begin(v), end(v)
#define compact(v) v.erase(unique(range(v)), end(v))
#define len(x) (int)(x).size()
#define BIT(x, i) ((x)>>(i)&1)
#define MASK(x) (1LL<<(x))

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;

template<class T> bool maximize(T& a, const T& b){ if(a<b) return a=b, true; return false; }
template<class T> bool minimize(T& a, const T& b){ if(a>b) return a=b, true; return false; }

const int N=1e5+5;

int n, m, s, t, U, V;
vector<pair<int, int>> g[N];
vector<int> rev[N];

vector<ll> dijkstra(int st){
  vector<ll> d(n+1, -1); d[st]=0;
  priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;
  pq.push({0, st});

  while(!pq.empty()){
    ll cost; int u;
    tie(cost, u)=pq.top(); pq.pop();
    if(cost!=d[u]) continue;
    for(int i=0; i<g[u].size(); ++i){
      int v=g[u][i].first, w=g[u][i].second;
      if(d[v]==-1 or d[v]>(d[u]+w)){
        d[v]=d[u]+w;
        pq.push({d[v], v});
      }
    }
  }
  return d;
}

void Zero_OP(){
  cin>>n>>m>>s>>t>>U>>V;

  if(n<=300){
    ll d[n+1][n+1];
    memset(d, 0x3f, sizeof(d));
    for(int i=1; i<=n; ++i) d[i][i]=0;

    for(int i=1; i<=m; ++i){
      int u, v; ll w; cin>>u>>v>>w;
      minimize(d[u][v], w);
      minimize(d[v][u], w);
    }

    for(int k=1; k<=n; ++k){
      for(int i=1; i<=n; ++i){
        for(int j=1; j<=n; ++j){
          minimize(d[i][j], d[i][k]+d[k][j]);
        }
      }
    }

    ll ans=d[U][V];
    for(int i=1; i<=n; ++i){
      for(int j=1; j<=n; ++j){
        if(d[s][i]+d[i][j]+d[j][t]==d[s][t]){
          minimize(ans, min(d[U][i]+d[j][V], d[V][i]+d[j][U]));
        }
      }
    }

    cout<<ans;
  }
  else {
    while(m--){
      int u, v, w; cin>>u>>v>>w;
      g[u].push_back({v, w});
      g[v].push_back({u, w});
    }
    vector<ll> d_u=dijkstra(U), d_v=dijkstra(V), d_t=dijkstra(t);
    priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<pair<ll, int>>> pq;
    vector<ll> d_s(n+1, -1); d_s[s]=0;
    pq.push({0, s});

    while(!pq.empty()){
      ll cost; int u;
      tie(cost, u)=pq.top();
      pq.pop();

      if(d_s[u]!=cost) continue;

      for(int i=0; i<g[u].size(); ++i){
        int v=g[u][i].first, w=g[u][i].second;
        if(d_s[v]==-1 or (d_s[v]>d_s[u]+w)){
          d_s[v]=d_s[u]+w;
          rev[v].clear();
          rev[v].push_back(u);
          pq.push({d_s[v], v});
        }
        else if(d_s[u]+w==d_s[v]) rev[v].push_back(u);
      }
    }

    ll ans=d_u[V];

    vector<ll> d(n+1, -1);
    d[t]=d_u[t];
    pq.push({d[t], t});
    while(!pq.empty()){
      ll cost; int u;
      tie(cost, u)=pq.top(); pq.pop();

      if(cost!=d[u]) continue;

      minimize(ans, d[u]+d_v[u]);

      for(int i=0; i<rev[u].size(); ++i){
        int v=rev[u][i];
        if(d[v]==-1 or d[v]>min(d[u], d_u[v])){
          d[v]=min(d[u], d_u[v]);
          pq.push({d[v], v});
        }
      }
    }

    d.resize(n+1, -1);
    d[t]=d_v[t];
    pq.push({d[t], t});
    while(!pq.empty()){
      ll cost; int u;
      tie(cost, u)=pq.top();
      pq.pop();
      if(cost!=d[u]) continue;

      for(int i=0; i<rev[u].size(); ++i){
        int v=rev[u][i];
        if(d[v]==-1 or d[v]>min(d[u], d_v[v])){
          d[v]=min(d[u], d_v[v]);
          pq.push({d[v], v});
        }
      }
    }

    cout<<ans;
  }
}

signed main(){
  ios_base::sync_with_stdio(0);
  cin.tie(NULL); cout.tie(NULL);

  #define task "COMPUTER_PASS"
  if(fopen(task".INP", "r")){
    freopen(task".INP", "r", stdin);
    freopen(task".OUT", "w", stdout);
  }

  int TC=1; //cin>>TC;
  while(TC--) Zero_OP();

  return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'std::vector<long long int> dijkstra(int)':
commuter_pass.cpp:33:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |     for(int i=0; i<g[u].size(); ++i){
      |                  ~^~~~~~~~~~~~
commuter_pass.cpp: In function 'void Zero_OP()':
commuter_pass.cpp:95:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |       for(int i=0; i<g[u].size(); ++i){
      |                    ~^~~~~~~~~~~~
commuter_pass.cpp:120:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |       for(int i=0; i<rev[u].size(); ++i){
      |                    ~^~~~~~~~~~~~~~
commuter_pass.cpp:138:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  138 |       for(int i=0; i<rev[u].size(); ++i){
      |                    ~^~~~~~~~~~~~~~
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:157:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  157 |     freopen(task".INP", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:158:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  158 |     freopen(task".OUT", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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