백준

5567 결혼식

n = int(input())
m = int(input())
f = [[] for i in range(n+1)]

ans = [1]
for i in range(m):
    a, b = map(int, input().split())
    f[a].append(b)
    f[b].append(a)
ans+=f[1]
for i in f[1]:
    ans += f[i]

print(len(set(ans))-1)

프로그래머스

전화번호 목록

def solution(phone_book):
    answer = True
    n = len(phone_book)
    phone_book = sorted(phone_book)
    for i in range(1, n):
        m = len(phone_book[i-1])
        if phone_book[i-1] == phone_book[i][:m]:
            answer = False
            break
    return answer

베스트앨범

from collections import defaultdict
import operator
def solution(genres, plays):
    g = defaultdict(int)
    arr = defaultdict(list)
    for i in range(len(genres)):
        g[genres[i]] += plays[i]
        arr[genres[i]].append((plays[i], i))
    g = sorted(g.items(), reverse=True, key=operator.itemgetter(1))
    answer = []
    for i in g:
        arr[i[0]].sort(key = lambda x : (-x[0], x[1]))
        print(arr[i[0]])
        answer.append(arr[i[0]][0][1])
        if len(arr[i[0]]) >= 2:
            answer.append(arr[i[0]][1][1])
        
    
    return answer