"""
출처:프로그래머스,
https://school.programmers.co.kr/learn/courses/30/lessons/258711
"""
# 풀이 과정
def solution(edges):
    result = [0, 0, 0, 0]
    g = {}
    e = edges  # 용어 축소

    for start, arrive in e:  # g[0]:start g[1]:arrive
        if not g.get(start):
            g[start] = [0, 0]
        if not g.get(arrive):
            g[arrive] = [0, 0]

        g[start][0] += 1
        g[arrive][1] += 1

    for key, val in g.items():
        # 정점 찾기
        if val[0] >= 2 and val[1] == 0:
            result[0] = key
        # 막대그래프 찾기
        elif val[0] == 0 and val[1] >= 1:
            result[2] += 1
        # 8자그래프 찾기
        elif val[0] >= 2 and val[1] >= 2:
            result[3] += 1
    # 도넛 그래프
    result[1] = (g[result[0]][0] - result[2] - result[3])

    return result