树

struct Tree{
	int n;
	vector<vector<pair<int, int>>> e;
	vector<int> dep, parent, maxdep, d1, d2, s1, s2, up;
	Tree(int n){
		this -> n = n;
		e.resize(n + 1);
		dep.resize(n + 1);
		parent.resize(n + 1);
		maxdep.resize(n + 1);
		d1.resize(n + 1);
		d2.resize(n + 1);
		s1.resize(n + 1);
		s2.resize(n + 1);
		up.resize(n + 1);
	}
	void add(int u, int v, int w){
		e[u].push_back({w, v});
		e[v].push_back({w, u});
	}
	void dfs(int u, int fa){
		maxdep[u] = dep[u];
		for (auto [w, v] : e[u]){
			if (v == fa) continue;
			dep[v] = dep[u] + 1;
			parent[v] = u;
			dfs(v, u);
			maxdep[u] = max(maxdep[u], maxdep[v]);
		}
	}
	
	void dfs1(int u, int fa){
		for (auto [w, v] : e[u]){
			if (v == fa) continue;
			dfs1(v, u);
			int x = d1[v] + w;
			if (x > d1[u]){
				d2[u] = d1[u], s2[u] = s1[u];
				d1[u] = x, s1[u] = v;
			}
			else if (x > d2[u]){
				d2[u] = x, s2[u] = v;
			}
		}
	}
	void dfs2(int u, int fa){
		for (auto [w, v] : e[u]){
			if (v == fa) continue;
			if (s1[u] == v){
				up[v] = max(up[u], d2[u]) + w;
			}
			else{
				up[v] = max(up[u], d1[u]) + w;
			}
			dfs2(v, u);
		}
	}
	
	int radius, center, diam;
	void getCenter(){
		center = 1;	//中心
		for (int i = 1; i <= n; i ++ ){
			if (max(d1[i], up[i]) < max(d1[center], up[center])){
				center = i;
			}
		}
		radius = max(d1[center], up[center]);	//距离最远点的距离的最小值
		diam = d1[center] + up[center] + 1;	//直径
	}
	
	int rem;	//删除重心后剩余连通块体积的最小值
	int cog;	//重心
	vector<bool> vis;
	void getCog(){
		vis.resize(n);
		rem = INT_MAX;
		cog = 1;
		dfsCog(1);
	}
	int dfsCog(int u){
		vis[u] = true;
		int s = 1, res = 0;
		for (auto [w, v] : e[u]){
			if (vis[v]) continue;
			int t = dfsCog(v);
			res = max(res, t);
			s += t;
		}
		res = max(res, n - s);
		if (res < rem){
			rem = res;
			cog = u;
		}
		return s;
	}
};