oj.uz

Submission #1026482

# Submission time Handle Problem Language Result Execution time Memory
1026482 2024-07-18T06:44:46 Z NeroZein Olympic Bus (JOI20_ho_t4) C++17
0 / 100
 58 ms 3912 KB 
#include "bits/stdc++.h"
using namespace std;
#define int long long

#ifdef Nero
#include "Deb.h"
#else
#define debug(...)
#endif

using pii = pair<int, int>;

const int N = 202;
const int INF = 2e12 + 12;

struct edge {
  int from, to, c, d;
};

int n, m;
int pe[N], pv[N];
vector<int> g[N];

vector<int> dijkstra(int src, vector<edge>& e) {
  vector<int> dist(n + 1, INF);
  dist[src] = 0; 
  priority_queue<pii, vector<pii>, greater<pii>> pq;
  pq.push({0, src});
  while (!pq.empty()) {
    auto [c, v] = pq.top();
    pq.pop();
    if (c != dist[v]) {
      continue; 
    }
    for (int i : g[v]) {
      int u = v ^ e[i].from ^ e[i].to;
      if (c + e[i].c < dist[u]) {
        pe[u] = i;
        pv[u] = v;
        dist[u] = c + e[i].c;
        pq.push({dist[u], u});
      }
    }
  }
  return dist;
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n >> m;
  vector<edge> e(m);
  for (int i = 0; i < m; ++i) {
    int u, v, c, d;
    cin >> u >> v >> c >> d;
    e[i] = {u, v, c, d}; 
    g[u].push_back(i); 
  }
  vector<bool> marked(m);
  vector<vector<int>> dist(n + 1); 
  dist[1] = dijkstra(1, e);
  if (dist[1][n] != INF) {
    int x = n;
    while (x != 1) {
      assert(pv[x] != 0);
      marked[pe[x]] = true;
      x = pv[x]; 
    }
  }
  for (int i = 1; i <= n; ++i) {
    pe[i] = pv[i] = 0; 
  }
  dist[n] = dijkstra(n, e);
  if (dist[n][1] != INF) {
    int x = 1;
    while (x != n) {
      assert(pv[x] != 0);
      marked[pe[x]] = true;
      x = pv[x]; 
    }    
  }
  int ans = INF;
  if (dist[1][n] != INF && dist[n][1] != INF) {
    ans = dist[1][n] + dist[n][1];
  }
  for (int i = 2; i < n; ++i) {
    dist[i] = dijkstra(i, e);
  }
  for (int i = 0; i < m; ++i) {
    if (marked[i]) {
      continue; 
    }
    int u = e[i].from, v = e[i].to; 
    if (dist[1][n] != INF && dist[n][v] != INF && dist[u][1] != INF) {
      ans = min(ans, e[i].d + dist[1][n] + dist[n][v] + e[i].c + dist[u][1]);
    }
    if (dist[1][v] != INF && dist[u][n] != INF && dist[n][1] != INF) {
      ans = min(ans, e[i].d + dist[1][v] + e[i].c + dist[u][n] + dist[n][1]);
    }
    if (dist[1][v] != INF && dist[u][n] != INF && dist[n][v] != INF && dist[u][1] != INF) {
      ans = min(ans, e[i].d + dist[1][v] + e[i].c + dist[u][n] + dist[n][v] + e[i].c + dist[u][1]);
    }
  }
  for (int i = 0; i < m; ++i) {
    if (!marked[i]) {
      continue; 
    }
    int u = e[i].from, v = e[i].to;
    g[u].erase(find(g[u].begin(), g[u].end(), i));
    g[v].push_back(i);
    swap(e[i].from, e[i].to);//useless, but for the logic
    dist[1] = dijkstra(1, e); 
    dist[n] = dijkstra(n, e);
    if (dist[1][n] != INF && dist[n][1] != INF) {
      ans = min(ans, dist[1][n] + dist[n][1]); 
    }
    g[v].pop_back();
    g[u].push_back(i);
    swap(e[i].from, e[i].to); 
  }
  if (ans == INF) {
    ans = -1; 
  }
  cout << ans << '\n'; 
  return 0;
}

Subtask #1
0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 920 KB Output is correct
2 Correct 1 ms 604 KB Output is correct
3 Incorrect 6 ms 696 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0 / 11.0

# Verdict Execution time Memory Grader output
1 Incorrect 58 ms 3848 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 668 KB Output is correct
2 Correct 1 ms 604 KB Output is correct
3 Correct 33 ms 3164 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 42 ms 3804 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 0 ms 348 KB Output is correct
8 Correct 30 ms 3912 KB Output is correct
9 Correct 31 ms 3820 KB Output is correct
10 Correct 35 ms 3720 KB Output is correct
11 Correct 34 ms 3728 KB Output is correct
12 Correct 34 ms 3812 KB Output is correct
13 Incorrect 1 ms 348 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #4
0 / 63.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 920 KB Output is correct
2 Correct 1 ms 604 KB Output is correct
3 Incorrect 6 ms 696 KB Output isn't correct
4 Halted 0 ms 0 KB -