加油～這是 python 數一數二最常使用到的工具了
一定要好好學習喔～～

• Number of occurrences

counter = {}
for word in input().split():
    counter[word] = counter.get(word, 0) + 1
    print(counter[word] - 1, end=' ')

• Dictionary of synonyms

n = int(input())
d = {}
for i in range(n):
    first, second = input().split()
    d[first] = second
    d[second] = first
print(d[input()])

• Elections in the USA

num_votes = {}
for _ in range(int(input())):
    candidate, votes = input().split()
    num_votes[candidate] = num_votes.get(candidate, 0) + int(votes)

for candidate, votes in sorted(num_votes.items()):
    print(candidate, votes)

• The most frequent word

counter = {}
for i in range(int(input())):
    line = input().split()
    for word in line:
        counter[word] = counter.get(word, 0) + 1
        
max_count = max(counter.values())
most_frequent = [k for k, v in counter.items() if v == max_count]
print(min(most_frequent))

• Access rights

OPERATION_PERMISSION = {
    'read': 'R',
    'write': 'W',
    'execute': 'X',
}

file_permissions = {}
for i in range(int(input())):
    file, *permissions = input().split()
    file_permissions[file] = set(permissions)

for i in range(int(input())):
    operation, file = input().split()
    if OPERATION_PERMISSION[operation] in file_permissions[file]:
        print('OK')
    else:
        print('Access denied')

• Countries and cities

motherland = {}
for i in range(int(input())):
    country, *cities = input().split()
    for city in cities:
        motherland[city] = country
        
for i in range(int(input())):
    print(motherland[input()])

• Frequency analysis

from collections import Counter

words = []
for _ in range(int(input())):
    words.extend(input().split())

counter = Counter(words)
pairs = [(-pair[1], pair[0]) for pair in counter.most_common()]
words = [pair[1] for pair in sorted(pairs)]
print('\n'.join(words))

• English-Latin dictionary

from collections import defaultdict

latin_to_english = defaultdict(list)
for i in range(int(input())):
    english_word, latin_translations_chunk = input().split(' - ')
    latin_translations = latin_translations_chunk.split(', ')
    for latin_word in latin_translations:
        latin_to_english[latin_word].append(english_word)
    
print(len(latin_to_english))
for latin_word, english_translations in sorted(latin_to_english.items()):
    print(latin_word + ' - ' + ', '.join(english_translations))