一共有3道题各位请教

1. 求从1-4中任选2个数组成的所有2位数。

2.从键盘输入一个字符串，统计该字符串中各字母出现的次数。

3.已知字符串weather中存放了若干以逗号分隔的天气，如weather=’sunny,rainny,windy,sunny,rainny,windy,sunny,windy,windy,sunny,sunny,windy’，统计每种天气出现的次数。

1

# 不可重复
list1 = []
for i in range(1,5):
    for j in range(1,i):
        list1.append(i * 10 + j)
        list1.append(j * 10 + i)
print(list1)
#
# 可重复
# list1 = []
# for i in range(1,5):
#     for j in range(1,i+1):
#         list1.append(i * 10 + j)
#         if i * 10 + j !=j * 10 + i:
#             list1.append(j * 10 + i)
# print(list1)

from itertools import permutations
for i in permutations("1234",2):
    print(int(''.join(i)))

from collections import Counter
s = input("请输入字符串：")
for k,v in Counter(s).items():
    print(f"{k}出现了{v}次")

weather='sunny,rainny,windy,sunny,rainny,windy,sunny,windy,windy,sunny,sunny,windy'
for k,v in Counter(weather.split(',')).items():
    print(f"{k}出现了{v}次")