[LeetCode] 680. Valid Palindrome II 验证回文字符串 II
Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome.
Example 1:
Input: "aba" Output: True
Example 2:
Input: "abca" Output: True Explanation: You could delete the character 'c'.
Note:
- The string will only contain lowercase characters a-z. The maximum length of the string is 50000.
125. Valid Palindrome 的拓展，给定一个非空字符串，最多可删除1个字符，判断是否可以变成回文。
解法：还是从首尾两边开始比较，如果匹配就移动指针继续比较。当遇到不匹配的时候，删除左边的字符或者右边的字符，只要有一种能匹配就继续。
Python：
class Solution(object):
def validPalindrome(self, s):
"""
:type s: str
:rtype: bool
"""
def validPalindrome(s, left, right):
while left < right:
if s[left] != s[right]:
return False
left, right = left+1, right-1
return True
left, right = 0, len(s)-1
while left < right:
if s[left] != s[right]:
return validPalindrome(s, left, right-1) or validPalindrome(s, left+1, right)
left, right = left+1, right-1
return True
C++：
class Solution {
public:
bool validPalindrome(string s) {
int left = 0, right = s.length() - 1;
while (left < right) {
if (s[left] != s[right]) {
return validPalindrome(s, left, right - 1) || validPalindrome(s, left + 1, right);
}
++left, --right;
}
return true;
}
private:
bool validPalindrome(const string& s, int left, int right) {
while (left < right) {
if (s[left] != s[right]) {
return false;
}
++left, --right;
}
return true;
}
};
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[LeetCode] 125. Valid Palindrome 验证回文字符串
