[백준 BOJ][JAVA] 2252번: 줄 세우기

https://www.acmicpc.net/problem/2252

2252번: 줄 세우기

 

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Scanner;
public class Main {
	public static void tSort(List<List<Integer>> list, int[] indegree) {
		Queue<Integer> queue= new LinkedList<>();
		Queue<Integer> result= new LinkedList<>();
		for(int i = 0;i < indegree.length; i++) {
			if(indegree[i] == 0) {
				queue.add(i);
			}
		}
		while(!queue.isEmpty()) {
			int node = queue.poll();
			result.add(node);
			
			for(int i = 0; i < list.get(node).size(); i++) {
				int n = list.get(node).get(i);
				indegree[n]--;
				
				if(indegree[n] == 0) {
					queue.add(n);
				}
			}
		}
		int size = result.size();
		for(int i = 0; i < size; i++) {
			System.out.print(result.poll() + 1 + " ");	
		}
	}
	
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int N = scan.nextInt();
		int M = scan.nextInt();
		List<List<Integer>> list = new ArrayList<List<Integer>>();
		int[] indegree = new int[N];
		for(int i = 0; i < N; i++) {
			list.add(new ArrayList());
		}
		
		for(int i = 0; i < M; i++) {
			int front = scan.nextInt() - 1;
			int back = scan.nextInt() - 1;
			list.get(front).add(back);
			indegree[back]++;
		}
		tSort(list, indegree);
		
		scan.close();
	}

}