最短路模版（dijkstra）

#include<cstdio>#include<cstring>#include<queue>using namespace std;const int INF = 1000000000;const int maxn = 1000 + 10;struct Edge {  int from, to, dist;};struct HeapNode {  int d, u;  bool operator < (const HeapNode& rhs) const {    return d > rhs.d;  }};struct Dijkstra {  int n, m;  vector<Edge> edges;  vector<int> G[maxn];  bool done[maxn];    // 是否已永久标号  int d[maxn];        // s到各个点的距离  int p[maxn];        // 最短路中的上一条弧  void init(int n) {    this->n = n;    for(int i = 0; i < n; i++) G[i].clear();    edges.clear();  }  void AddEdge(int from, int to, int dist) {    edges.push_back((Edge){from, to, dist});    m = edges.size();    G[from].push_back(m-1);  }  void dijkstra(int s) {    priority_queue<HeapNode> Q;    for(int i = 0; i < n; i++) d[i] = INF;    d[s] = 0;    memset(done, 0, sizeof(done));    Q.push((HeapNode){0, s});    while(!Q.empty()) {      HeapNode x = Q.top(); Q.pop();      int u = x.u;      if(done[u]) continue;      done[u] = true;      for(int i = 0; i < G[u].size(); i++) {        Edge& e = edges[G[u][i]];        if(d[e.to] > d[u] + e.dist) {          d[e.to] = d[u] + e.dist;          p[e.to] = G[u][i];          Q.push((HeapNode){d[e.to], e.to});        }      }    }  }};