指针写的链式前向星，看上去可能有些另类。。。

手算了一下内存，不应该超的。不知怎么就 MLE 了。求教。

#include <cstdio>
#include <cstring>
#include <cmath>
#include <cfloat>

#include <vector>
#include <algorithm>

template <class T>
inline T readint() {
	T ret = 0; int ch = getchar(); bool negative = false;
	while (ch < '0' || ch > '9') { if (ch == '-') negative = true; if (ch == EOF) return EOF; ch = getchar(); }
	while (ch >= '0' && ch <= '9') ret = (ret << 1) + (ret << 3) + ch - 48, ch = getchar();
	return negative ? -ret : ret;
}

#define NAMESPACE_BEGIN(ns)	namespace ns {
#define NAMESPACE_END		}

NAMESPACE_BEGIN(graph)

struct Edge { int to; bool bridge; Edge* next; Edge* inv; };

Edge* createEdge(int to, Edge* next) {
	Edge* e = new Edge;
	e->to = to, e->bridge = false, e->next = next, e->inv = nullptr;
	return e;
}

struct Graph { int ver; Edge** edge; };

Graph* createGraph(int ver) {
	Graph* g = new Graph;
	g->ver = ver, g->edge = new Edge*[ver + 1];
	memset(g->edge, 0, sizeof(Edge*) * (ver + 1));
	return g;
}

inline void addEdgeUndirected(Graph* g, int u, int v) {
	g->edge[u] = createEdge(v, g->edge[u]);
	g->edge[v] = createEdge(u, g->edge[v]);
	g->edge[u]->inv = g->edge[v];
	g->edge[v]->inv = g->edge[u];
}

NAMESPACE_BEGIN(dcc)

struct DCCInfo {
	Graph* g;
	int timestamp; int* rank; int* low;
	int cntedcc; int* edcc; std::vector<int>* contain;
};

DCCInfo* create(Graph* g) {
	DCCInfo* dcc = new DCCInfo;
	dcc->g = g, dcc->timestamp = dcc->cntedcc = 0;
	dcc->rank = new int[g->ver + 1];
	dcc->low = new int[g->ver + 1];
	dcc->edcc = new int[g->ver + 1];
	memset(dcc->rank, -1, sizeof(int) * (g->ver + 1));
	memset(dcc->edcc, -1, sizeof(int) * (g->ver + 1));
	return dcc;
}

void tarjan(DCCInfo* dcc, int p, Edge* ecur) {
	dcc->rank[p] = dcc->low[p] = ++dcc->timestamp;

	for (Edge* e = dcc->g->edge[p]; e; e = e->next)
		if (dcc->rank[e->to] == -1) {
			tarjan(dcc, e->to, e);
			dcc->low[p] = std::min(dcc->low[p], dcc->low[e->to]);
			if (dcc->low[e->to] > dcc->rank[p])
				e->bridge = e->inv->bridge = true;
		} else if (!ecur || e != ecur->inv)
			dcc->low[p] = std::min(dcc->low[p], dcc->rank[e->to]);
}

void fill(DCCInfo* dcc, int p, int edcc) {
	dcc->edcc[p] = edcc;
	for (Edge* e = dcc->g->edge[p]; e; e = e->next)
		if (dcc->edcc[e->to] == -1 && !e->bridge)
			fill(dcc, e->to, edcc);
}

void exec_tarjan(DCCInfo* dcc) {
	for (int p = 1; p <= dcc->g->ver; ++p)
		if (dcc->rank[p] == -1) 
			tarjan(dcc, p, nullptr);

	delete[] dcc->rank;
	delete[] dcc->low;
	for (int p = 1; p <= dcc->g->ver; ++p)
		if (dcc->edcc[p] == -1)
			fill(dcc, p, ++dcc->cntedcc);

	dcc->contain = new std::vector<int>[dcc->cntedcc + 1];
	for (int p = 1; p <= dcc->g->ver; ++p)
		dcc->contain[dcc->edcc[p]].push_back(p);
	delete[] dcc->edcc;
}

NAMESPACE_END

NAMESPACE_END

int main(int argc, char *argv[]) {
	int nver = readint<int>();
	int nedge = readint<int>();

	graph::Graph* g = graph::createGraph(nver);
	for (int e = 0, u, v; e < nedge; ++e) {
		u = readint<int>();
		v = readint<int>();
		graph::addEdgeUndirected(g, u, v);
	}

	graph::dcc::DCCInfo* dcc = graph::dcc::create(g);
	graph::dcc::exec_tarjan(dcc);

	printf("%d\n", dcc->cntedcc);
	for (int c = 1; c <= dcc->cntedcc; ++c) {
		printf("%d ", dcc->contain[c].size());
		for (auto it = dcc->contain[c].begin(); it != dcc->contain[c].end(); ++it)
			printf("%d%c", *it, " \n"[it == --dcc->contain[c].end()]);
	}

	delete[] dcc->contain;

	return 0;
}