# leetcode 1616. Split Two Strings to Make Palindrome （python）

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### 描述

You are given two strings a and b of the same length. Choose an index and split both strings at the same index, splitting a into two strings: aprefix and asuffix where a = aprefix + asuffix, and splitting b into two strings: bprefix and bsuffix where b = bprefix + bsuffix. Check if aprefix + bsuffix or bprefix + asuffix forms a palindrome.

When you split a string s into sprefix and ssuffix, either ssuffix or sprefix is allowed to be empty. For example, if s = "abc", then "" + "abc", "a" + "bc", "ab" + "c" , and "abc" + "" are valid splits.

Return true if it is possible to form a palindrome string, otherwise return false.

Notice that x + y denotes the concatenation of strings x and y.

Example 1:

• Input: a = "x", b = "y"
• Output: true
• Explaination: If either a or b are palindromes the answer is true since you can split in the following way:
• aprefix = "", asuffix = "x"
• bprefix = "", bsuffix = "y"
• Then, aprefix + bsuffix = "" + "y" = "y", which is a palindrome.

Example 2:

• Input: a = "abdef", b = "fecab"
• Output: true

Example 3:

• Input: a = "ulacfd", b = "jizalu"

• Output: true

• Explaination: Split them at index 3:

• aprefix = "ula", asuffix = "cfd"

• bprefix = "jiz", bsuffix = "alu"

• Then, aprefix + bsuffix = "ula" + "alu" = "ulaalu", which is a palindrome.

Example 4:

• Input: a = "xbdef", b = "xecab"
• Output: false

Note:

1 <= a.length, b.length <= 10^5
a.length == b.length
a and b consist of lowercase English letters

### 解析

• a：AB | CD | EF
• b：GH | KJ | LM

### 解答

class Solution(object):
def checkPalindromeFormation(self, a, b):
"""
:type a: str
:type b: str
:rtype: bool
"""
return self.check(a, b) or self.check(b,a)

def check(self, a, b):
if len(a) == 1 : return True
i = 0
j = len(a) - 1
while i<=j and a[i]==b[j]:
i+=1
j-=1
if i>j:return True
return self.isPalindrome(a[i:j+1]) or self.isPalindrome(b[i:j+1])

def isPalindrome(self, s):
i = 0
j = len(s)-1
while i<=j and s[i]==s[j]:
i+=1
j-=1
return i>j

### 运行结果

Runtime: 119 ms, faster than 66.67% of Python online submissions for Split Two Strings to Make Palindrome.
Memory Usage: 15.6 MB, less than 38.10% of Python online submissions for Split Two Strings to Make Palindrome.