[Baekjoon-Python] 2252 : 줄 세우기

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

접근

위상 정렬 알고리즘을 사용한다.

풀이

from sys import stdin
from collections import deque


def topological_sort():
    q = deque()
    for i in range(1, N + 1):
        if in_degree[i] == 0:
            q.append(i) # (1)

    while q:
        node = q.popleft()
        print(node, end=" ")

        for i in graph[node]: # (2)
            in_degree[i] -= 1
            if in_degree[i] == 0:
                q.append(i)


N, M = map(int, stdin.readline().split())
graph = [[] for _ in range(N + 1)]
in_degree = [0] * (N + 1)

for _ in range(M):
    a, b = map(int, stdin.readline().split())
    graph[a].append(b)
    in_degree[b] += 1 # (3)

topological_sort()