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#include <iostream>
#include <fstream>
#include <queue>
#include <bitset>
#include <vector>
#include <stack>
#include <algorithm>
#define maxSize 100001
using namespace std;
vector<vector<int>> readAdjacencyList(ifstream &fin, int nodes, int edges, bool isDirected = false) {
vector<vector<int>> adjList(nodes + 1);
for (int i = 0; i < edges; i++) {
int x, y;
fin >> x >> y;
adjList[x].push_back(y);
if (!isDirected) {
adjList[y].push_back(x);
}
}
return adjList;
}
vector<vector<int>> transposeGraph(const vector<vector<int>>& adjList) {
int nodes = adjList.size();
vector<vector<int>> transposed(nodes);
for (int i = 1; i < nodes; i++) {
for (const auto& neighbor : adjList[i]) {
transposed[neighbor].push_back(i);
}
}
return transposed;
}
void depthFirstSearch(const vector<vector<int>>& adjList, int node, bitset<maxSize>& marked, stack<int>& topOrd) {
marked[node] = true;
for (auto neighbor : adjList[node]) {
if (!marked[neighbor]) {
depthFirstSearch(adjList, neighbor, marked, topOrd);
}
}
topOrd.push(node);
}
void dsfComponent(const vector<vector<int>>& transposed, int node, bitset<maxSize>& marked, vector<int>& component) {
marked[node] = true;
component.push_back(node);
for (const auto& neighbor : transposed[node]) {
if (!marked[neighbor]) {
dsfComponent(transposed, neighbor, marked, component);
}
}
}
vector<vector<int>> kosarajuAlgorithm(const vector<vector<int>>& adjList) {
bitset<maxSize> marked;
stack<int> topOrd;
for (int i = 1; i < adjList.size(); i++) {
if(!marked[i]) {
depthFirstSearch(adjList, i, marked, topOrd);
}
}
vector<vector<int>> transposed = transposeGraph(adjList);
marked.reset();
vector<vector<int>> stronglyConnectedComponents;
while (!topOrd.empty()) {
int node = topOrd.top();
topOrd.pop();
if (!marked[node]) {
vector<int> component;
dsfComponent(transposed, node, marked, component);
stronglyConnectedComponents.push_back(component);
}
}
return stronglyConnectedComponents;
}
int main() {
ifstream fin("ctc.in");
ofstream fout("ctc.out");
int nodes, edges;
fin >> nodes >> edges;
auto adjList = readAdjacencyList(fin, nodes, edges, true);
auto stronglyConnectedComponents = kosarajuAlgorithm(adjList);
for (const auto& component : stronglyConnectedComponents) {
for (const auto& node : component) {
fout << node << " ";
}
fout << endl;
}
fin.close();
fout.close();
return 0;
}