#把英字母都存入字典內，並對應其出現的次數
str = 'tomorrow'
#方法1：for s in str....（a[鍵] = 值)
a = dict()
for s in str:
    a[s] = str.count(s)
print(a)

#方法2：{鍵:值 for s in ttr}}
#b = dict()
b = {s:str.count(s) for s in str}
print(b)