BOJ 11779: 최소비용 구하기 2

작성일

https://www.acmicpc.net/problem/11779

  • 3월동안 210문제 풀기 (10/210)
  • 경로를 복원하는 본격 다익스트라
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#include <bits/stdc++.h>
using namespace std;

class Graph {
  struct Edge {
    int v, dist;
  };

  int N, INF = 1e9;
  vector<vector<Edge>> adj;
public:

  Graph(int n): N(n), adj(n+1) {}

  void addEdge(int u, int v, int dist) {
    adj[u].push_back({v,dist});
  }

  struct Node {
    int u, dist;
    bool operator<(const Node& b) const {
      return dist > b.dist;
    }
  };

  vector<int> dijkstra(int s, vector<int>& dist) {
    dist = vector<int>(N+1, INF);
    vector<int> par(N+1, -1);
    priority_queue<Node> pq;
    pq.push({s, 0});
    dist[s] = 0;

    while(pq.size()) {
      Node cur = pq.top(); pq.pop();
      if(cur.dist != dist[cur.u])
        continue;

      for(Edge& e: adj[cur.u]) {
        if(dist[e.v] > cur.dist + e.dist) {
          dist[e.v] = cur.dist + e.dist;
          pq.push({e.v, dist[e.v]});
          par[e.v] = cur.u;
        }
      }
    }
    return par;
  }
};


int main() {
  int N, M, s, e, u, v, cost;
  scanf("%d %d", &N, &M);
  Graph graph(N);
  for(int i = 0; i < M; i++) {
    scanf("%d %d %d", &u, &v, &cost);
    graph.addEdge(u,v,cost);
  }
  scanf("%d %d", &s, &e);

  vector<int> dist;
  auto par = graph.dijkstra(s, dist);
  printf("%d\n", dist[e]);

  int cur = e;
  vector<int> path = {e};
  while(cur != s) {
    cur = par[cur];
    path.push_back(cur);
  }
  printf("%d\n", path.size());
  for(int i = path.size()-1; i >= 0; i--)
    printf("%d ", path[i]);
}