a = 'abcdefccdd' ，展示的结果：{'a':2,

# a = 'abcdefccdd'
# 展示的结果：{'a':2, 'b':3, 'd':4}
a = 'abcdefccdd'
a_dict={}
cnt=0
for i in a:
    if i not in a_dict:
        # a_dict[i] = 1
        a_dict.update({i:1})
    else:
        a_dict[i]+=1
print(a_dict)