문제 : https://programmers.co.kr/learn/courses/30/lessons/42579

▶ 딕셔너리 value값으로 정렬 하기 : https://kkamikoon.tistory.com/138

→ 딕셔너리를 정렬하는 순간 리스트 형태로 바뀐다.

▶ 코드

# 장르별로 두개씩 모아 베스트 앨범을 출시 

import operator

def solution(genres, plays):
    ans = []
    dic = {}
    for a, b in zip(genres, plays):
        if a in dic.keys():
            dic[a] += b
        else:
            dic[a] = b
    #print(dic) # {'classic': 1450, 'pop': 3100}
    sdic = sorted(dic.items(), key=operator.itemgetter(1), reverse=True)
    #print(sdic) # [('pop', 3100), ('classic', 1450)]
    for a in sdic:
        c = 0
        target = a[0]
        #print(target)
        tmp_dic = {}
        index = -1
        for i in range(len(genres)):
            
            if genres[i] == target:
                index = i
                tmp_dic[index] = plays[index]
        #print(tmp_dic) # {1: 600, 4: 2500}
        #print(index)
                
        if len(tmp_dic) == 1:
            ans.append(index)
            continue

        tmp_dic = sorted(tmp_dic.items(), key=operator.itemgetter(1), reverse=True)
        #print(tmp_dic) # [(4, 2500), (5, 2500), (1, 600)]
        c = 0
        i = 0
        while c < 2:
            ans.append(tmp_dic[i][0])
            c += 1
            i += 1
    #print(ans)
    return ans        

#solution(['classic', 'pop', 'classic', 'classic', 'pop', 'pop'], [500, 600, 150, 800, 2500, 2500])
#solution(['classic','pop','classic','classic','pop'],[500,600,501,800,900])

문제 : https://programmers.co.kr/learn/courses/30/lessons/42577

▶ 코드

def solution(phone_book):
    
    phone_book.sort()  # 숫자로된 문자열을 sort()하면, 앞 숫자 순서대로 정렬.. 
    #print(phone_book) # ['119', '11955678484', '7777', '9876532']

    for p1, p2 in zip(phone_book, phone_book[1:]): # ['119', '11955678484', '7777', '9876532'] 와 ['11955678484', '7777', '9876532']이 하나씩 짝을 이룸
        #print(p1, p2)
        if p2.startswith(p1):
            return False
    return True

#solution(["7777", "119","9876532","11955678484"])

문제 : https://programmers.co.kr/learn/courses/30/lessons/42576

▶ 코드

from collections import Counter

def solution(p, c):
    p_counter = Counter(p)
    c_counter = Counter(c)

    for a in p_counter.keys():
        if p_counter[a] != c_counter[a]:
            return str(a)

#solution(['mislav', 'stanko', 'mislav', 'ana'], ['stanko', 'ana', 'mislav'])