文章作者：Tyan
博客：noahsnail.com | CSDN | 简书
1. Description
Custom Sort String
2. Solution
解析：Version 1，Python3 3.6之后字典是有序的，因此先根据order构建一个有序字典，遍历str，将在order中的字符放到字典中，不存在的放到最终结果的前面，最后遍历字典，合并字符串。Version 2利用python自带的排序。
- Version 1
class Solution:
def customSortString(self, order: str, str: str) -> str:
dictionary = {ch: [] for ch in order}
ans = ''
for ch in str:
if ch in dictionary:
dictionary[ch].append(ch)
else:
ans += ch
for val in dictionary.values():
ans += ''.join(val)
return ans
- Version 2
class Solution:
def customSortString(self, order: str, str: str) -> str:
mapping = {}
for index, val in enumerate(order):
mapping[val] = index
s1 = ''
s2 = ''
for ch in str:
if ch in mapping:
s1 += ch
else:
s2 += ch
return ''.join(sorted(s1, key=lambda ch: mapping[ch])) + s2
