方法1-常规

s = input()

# 初始化计数器
alpha, space, digit, other = 0, 0, 0, 0

# 遍历字符串,统计各类字符的个数
for char in s:
    if char.isalpha():
        alpha += 1
    elif char.isspace():
        space += 1
    elif char.isdigit():
        digit += 1
    else:
        other += 1

print(alpha)
print(space)
print(digit)
print(other)

方法2-正则表达式

import re
s = input()
print(len(re.findall(r'[a-zA-Z]', s)))
print(len(re.findall(r'\s', s)))
print(len(re.findall(r'\d', s)))
print(len(re.findall(r'[^a-zA-Z0-9\s]', s)))