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TopologicalSort.java
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83 lines (76 loc) · 2.47 KB
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import java.lang.*;
import java.io.*;
import java.util.*;
class TopologicalSort {
public static void main(String[] args) throws IOException {
BufferedReader read =
new BufferedReader(new InputStreamReader(System.in));
int t = Integer.parseInt(read.readLine());
while (t-- > 0) {
ArrayList<ArrayList<Integer>> list = new ArrayList<>();
String st[] = read.readLine().trim().split("\\s+");
int edg = Integer.parseInt(st[0]);
int nov = Integer.parseInt(st[1]);
for (int i = 0; i < nov + 1; i++)
list.add(i, new ArrayList<Integer>());
String s[] = read.readLine().trim().split("\\s+");
int p = 0;
for (int i = 1; i <= edg; i++) {
int u = Integer.parseInt(s[p++]);
int v = Integer.parseInt(s[p++]);
list.get(u).add(v);
}
int[] res = new TopologicalSortUtil().topoSort(list, nov);
if (check(list, nov, res) == true)
System.out.println("1");
else
System.out.println("0");
}
}
static boolean check(ArrayList<ArrayList<Integer>> list, int V, int[] res) {
int[] map = new int[V];
for (int i = 0; i < V; i++) {
map[res[i]] = i;
}
for (int i = 0; i < V; i++) {
for (int v : list.get(i)) {
if (map[i] > map[v]) return false;
}
}
return true;
}
}
class TopologicalSortUtil {
static int[] topoSort(ArrayList<ArrayList<Integer>> adj, int N) {
int[] indegree = new int[N];
for(int i=0; i<N; i++) {
ArrayList<Integer> temp = adj.get(i);
for(int node : temp) {
indegree[node]++;
}
}
Queue<Integer> q = new LinkedList<>();
for(int i=0; i<N; i++) {
if(indegree[i] == 0) {
q.add(i);
}
}
int visited = 0;
ArrayList<Integer> result = new ArrayList<>();
while(!q.isEmpty()) {
int u = q.poll();
result.add(u);
for(int node : adj.get(u)) {
if(--indegree[node] == 0) {
q.add(node);
}
}
visited++;
}
int[] arr = new int[result.size()];
for(int i=0; i<result.size(); i++) {
arr[i] = result.get(i);
}
return arr;
}
}