【codewars】Mumbling

instruction

This time no story, no theory. The examples below show you how to write function

Examples:

my solution

def accum(s):
# your code
n = 0
reStr=""
for str in s:
if n!=0:
reStr = reStr + "-"
reStr = reStr + str.upper()
for i in range(n):
reStr = reStr + str.lower()
n = n+1
return reStr

best solution from others

def accum(s):
return '-'.join((a * i).title() for i, a in enumerate(s, 1))

join方法

用于将序列中的元素以指定的字符连接生成一个新的字符串

str.join(sequence)

sequence – 要连接的元素序列

c = "abc"
d = "-".join(c + "efg")
print(d)

>> a-b-c-e-f-g

c = ["abc","efg"]
d = "-".join(c)
print(d)

>> abc-efg

c = ["abc","efg"]
d = "-".join(c + "efg")
print(d)

>>    d = "-".join(c + "efg")
TypeError: can only concatenate list (not "str") to list

enumerate方法

将一个可遍历的数据对象(如列表、元组或字符串)组合为一个索引序列，同时列出数据和数据下标，一般用在 for 循环当中

enumerate(sequence, [start=0])

sequence – 一个序列、迭代器或其他支持迭代对象

start – 下标起始位置

s = "ABC"
for i, a in enumerate(s, 1):
print("i :",i," a:",a)

>>
i : 1  a: A
i : 2  a: B
i : 3  a: C

s = ["ABC","DEF"]
for i, a in enumerate(s, 1):
print("i :",i," a:",a)

>>
i : 1  a: ABC
i : 2  a: DEF

title方法

返回”标题化”的字符串,就是说所有单词都是以大写开始，其余字母均为小写

str.title()

strs = "abcdef".title()
print(strs)

>>Abcdef

代码行

‘-‘.join((a * i).title() for i, a in enumerate(s, 1))

print([str(i) for i in range(5)])

>> ['0', '1', '2', '3', '4']

xyz = "-".join([str(i) for i in range(5)])
print(xyz)

>> 0-1-2-3-4

s = "abcde"
k = [(a * i).title() for i, a in enumerate(s, 1)]
print(k)

>> ['A', 'Bb', 'Ccc', 'Dddd', 'Eeeee']

s = "abcde"
k = "-".join([(a * i).title() for i, a in enumerate(s, 1)])
print(k)

>> A-Bb-Ccc-Dddd-Eeeee