Submission #920138

#	Time	Username	Problem	Language	Result	Execution time	Memory
920138		vjudge1	Olympic Bus (JOI20_ho_t4)	C++17	100 / 100	872 ms	8640 KiB

ho_t4

/* Author : Mychecksdead  */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
const int N = 2000+100, M = 1e5+10, K = 52, MX = 30;
 
 
 
int n, m;
vector<array<ll, 4>> g[N], r[N];
vector<array<ll, 4>> E;
ll d1[N], d2[N], d3[N], d4[N];
vector<bool> in;
void solve(){
  cin >> n >> m;
  in.resize(m);
  for(int i = 0; i < m; ++i){
    int u, v, c, d; cin >> u >> v >> c >> d;
    g[u].pb({v, c, d, i});
    r[v].pb({u, c, d, i});
    E.pb({u, v, c, d});
  }
  for(int i = 1; i <= n; ++i) d1[i] = d2[i] = d3[i] = d4[i] = 1e15;
  
  vector<bool> used(n+1);
  priority_queue<array<ll, 3>> Q;
 
  Q.push({0, 1, -1});
  d1[1] = 0;
  while(!Q.empty()){
    int v = Q.top()[1]; int e = Q.top()[2]; Q.pop();
    if(used[v]) continue;
    if(e >= 0)
      in[e] = 1;
    used[v] = 1;
    for(auto U: g[v]){
      int u = U[0];
      if(d1[u] > d1[v] + U[1]){
        d1[u] = d1[v] + U[1];
        Q.push({-d1[u], u, U[3]});
      }
    }
  }
 
  fill(all(used), false);
  Q.push({0, 1, -1});
  d3[1] = 0;
  while(!Q.empty()){
    int v = Q.top()[1]; int e = Q.top()[2]; Q.pop();
    if(used[v]) continue;
    if(e >= 0)
      in[e] = 1;
    used[v] = 1;
    for(auto U: r[v]){
      int u = U[0];
      if(d3[u] > d3[v] + U[1]){
        d3[u] = d3[v] + U[1];
        Q.push({-d3[u], u, U[3]});
      }
    }
  }
 
  fill(all(used), false);
  Q.push({0, n, -1});
  d2[n] = 0;
  while(!Q.empty()){
    int v = Q.top()[1]; int e = Q.top()[2]; Q.pop();
    if(used[v]) continue;
    if(e >= 0)
      in[e] = 1;
    used[v] = 1;
    for(auto U: g[v]){
      int u = U[0];
      if(d2[u] > d2[v] + U[1]){
        d2[u] = d2[v] + U[1];
        Q.push({-d2[u], u, U[3]});
      }
    }
  }
 
  fill(all(used), false);
  Q.push({0, n, -1});
  d4[n] = 0;
  while(!Q.empty()){
    int v = Q.top()[1]; int e = Q.top()[2]; Q.pop();
    if(used[v]) continue;
    if(e >= 0)
      in[e] = 1;
    used[v] = 1;
    for(auto U: r[v]){
      int u = U[0];
      if(d4[u] > d4[v] + U[1]){
        d4[u] = d4[v] + U[1];
        Q.push({-d4[u], u, U[3]});
      }
    }
  }
 
  ll ans = d1[n] + d2[1];
  // cout << d1[n] << ' ' << d2[1] << '\n';
 
  for(int i = 0; i < m; ++i){
    int u = E[i][0], v = E[i][1];
    ll w = E[i][2], d = E[i][3];
    if(in[i]){
      fill(all(used), false);
      vector<ll> D(n+1, 1e15), D1(n+1, 1e15);
      D[1] = 0;
      Q.push({0, 1, -1});
      while(!Q.empty()){
        int x = Q.top()[1]; Q.pop();
        if(used[x]) continue;
        used[x] = 1;
        for(auto U: g[x]){
          if(U[3] == i) continue;
          int y = U[0];
          if(D[y] > D[x] + U[1]){
            D[y] = D[x] + U[1];
            Q.push({-D[y], y, -1});
          }
        }
        if(x == v){
          if(D[u] > D[v] + w){
            D[u] = D[v] + w;
            Q.push({-D[u], u, -1});
          }
        }
      }
      fill(all(used), false);
      D1[n] = 0;
      Q.push({0, n, -1});
      while(!Q.empty()){
        int x = Q.top()[1]; Q.pop();
        if(used[x]) continue;
        used[x] = 1;
        for(auto U: g[x]){
          if(U[3] == i) continue;
          int y = U[0];
          if(D1[y] > D1[x] + U[1]){
            D1[y] = D1[x] + U[1];
            Q.push({-D1[y], y, -1});
          }
        }
        if(x == v){
          if(D1[u] > D1[v] + w){
            D1[u] = D1[v] + w;
            Q.push({-D1[u], u, -1});
          }
        }
      }
      ans = min(ans, D[n] + D1[1] + d);
      // for(int i = 1; i <= n; ++i) cout << D[i] << ' ';
      // en;
    }else{
      ans = min({
        ans,
        d1[v] + d4[u] + d + w + min(d2[1], d2[v] + d3[u] + w),
        min(d1[n], d1[v] + d4[u] + w) + d2[v] + d3[u] + d + w
      });
    }
  }
  // for(int i = 1; i <= n; ++i){
    // cout << d1[i] << ' ' << d2[i] << '\n';
  // }
 
  cout << (ans > 1e10 ? -1 : ans);
}
 
 
 
int main(){
  cin.tie(0); ios::sync_with_stdio(0);
  int tt = 1, aa;
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  while(tt--){
    solve();
    // en;
    en;
  }
  cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
  return 0;
} 

Compilation message (stderr)

ho_t4.cpp: In function 'int main()':
ho_t4.cpp:178:15: warning: unused variable 'aa' [-Wunused-variable]
  178 |   int tt = 1, aa;
      |               ^~

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63