- 链星
  ```c
  inline void add_edge(int u, int v, int w) {
    edge[cnt].next = head[u]; edge[cnt].v = v; edge[cnt].w = w; head[u] = cnt++;
  }
  ```
- Dijkstra最短路
	- 要求：边权非负（不仅仅是没有负环）
	- 随手敲一个
	  ```c
	  priority_queue<node, vector<node>, greater<node>> pq;
	  pq.push({s, 0});
	  dis[s] = 0;
	  while(!pq.empty()) {
	    int u = pq.top().id;
	    pq.pop();
	    if (vis[u]) continue;
	    vis[u] = true;
	    for (int i = head[u]; i; i = edge[i].next) {
	      int v = edge[i].to;
	      if (dis[v] > dis[u] + edge[i].w) {
	        dis[v] = dis[u] + edge[i].w;
	        pq.push({v, dis[v]});
	      }
	    }
	  }
	  ```
- Kruscal生成树
	- ```c++
	  std::sort(e + 1, e + e_cnt + 1);
	  int ans = 0, t_cnt = 0;
	  for (int i = 1; i <= n; ++ i) fa[i] = i;
	  for (int i = 1; i <= e_cnt; ++ i) {
	    int fau = findfa(e[i].u);
	    int fav = findfa(e[i].v);
	    if (fau != fav) {
	      fa[fav] = fau; // attention! use fa[find(v)], not fa[v]
	      ans += e[i].w;
	      t_cnt ++;
	    }
	  }
	  ```