题解 | #使用字典计数#

# 记录输入的字符串
string = input()
# 用于保存每个字母次数的字典，key为字母，value为字母出现的次数
letter_num = {}

for i in string:
    # 当字母之前不存在时，为字典新增键值对，赋值为1
    if i not in letter_num.keys():
        letter_num[i] = 1
    # 已存在的字符，数量加1
    else:
        letter_num[i] += 1

print(letter_num)