标签：put ring bre self pad hello rate join code
Write a function that takes a string as input and reverse only the vowels of a string.
Example 1:
Given s = "hello", return "holle".
Example 2:
Given s = "leetcode", return "leotcede".
Note:
The vowels does not include the letter "y".
class Solution(object):
def reverseVowels(self, s):
"""
:type s: str
:rtype: str
"""
arr = list(s)
vows = {"a", "e", "i", "o", "u"}
i, j = 0, len(arr)-1
while i<j:
if arr[i].lower() in vows:
if arr[j].lower() in vows:
arr[i], arr[j] = arr[j], arr[i]
i += 1
j -= 1
else:
i += 1
return "".join(arr)
or
class Solution(object):
def reverseVowels(self, s):
"""
:type s: str
:rtype: str
"""
arr = list(s)
vows = {"a", "e", "i", "o", "u"}
i, j = 0, len(arr)-1
while i<j:
if arr[i].lower() in vows:
while i<j and arr[j].lower() not in vows:
j -= 1
if i == j: break
arr[i], arr[j] = arr[j], arr[i]
j -= 1
i += 1
return "".join(arr)
or 都用贪心：
class Solution(object):
def reverseVowels(self, s):
"""
:type s: str
:rtype: str
"""
arr = list(s)
vows = {"a", "e", "i", "o", "u"}
i, j = 0, len(arr)-1
while i<j:
while i<j and arr[i].lower() not in vows:
i += 1
while i<j and arr[j].lower() not in vows:
j -= 1
if i < j:
arr[i], arr[j] = arr[j], arr[i]
j -= 1
i += 1
return "".join(arr)
或者是two sum的思路，
class Solution(object):
def reverseVowels(self, s):
"""
:type s: str
:rtype: str
"""
arr = list(s)
vows = {"a", "e", "i", "o", "u", "A", "E", "I", "O", "U"}
i, j = 0, len(arr)-1
while i<j:
l, r = arr[i] in vows, arr[j] in vows
if l and r:
arr[i], arr[j] = arr[j], arr[i]
j -= 1
i += 1
elif l and not r:
j -= 1
elif not l and r:
i += 1
else:
i += 1
j -= 1
return "".join(arr)
此外，还有使用stack存储vows的做法，两次遍历，第一次生成stack，第二次在遇到vows时候直接pop stack里的字符替换掉。
class Solution(object):
def reverseVowels(self, s):
"""
:type s: str
:rtype: str
"""
arr = list(s)
vows = {"a", "e", "i", "o", "u", "A", "E", "I", "O", "U"}
stack = []
for i,c in enumerate(arr):
if c in vows:
stack.append(c)
for i,c in enumerate(arr):
if c in vows:
arr[i] = stack.pop()
return "".join(arr)
leetcode 345. Reverse Vowels of a String
标签：put ring bre self pad hello rate join code
原文地址：https://www.cnblogs.com/bonelee/p/9206297.html
