leetcode--Palindrome Partitioning

1.题目描述

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.   For example, "A man, a plan, a canal: Panama" is a palindrome. "race a car" is not a palindrome.   Note: Have you consider that the string might be empty? This is a good question to ask during an interview.   For the purpose of this problem, we define empty string as valid palindrome.

2.解题思路

题目很简单，但是就是要注意考虑到大小写和空字符串的问题（空字符串包括删除无用字符串之后为空的情况）

class Solution { public: bool isPalindrome(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function if(s.empty())return true; string s_argument; s_argument.push_back('#'); for(int i=0;i<s.length();++i) { if((s[i]<='z'&&s[i]>='a')||(s[i]>='0'&&s[i]<='9')||(s[i]>='A'&&s[i]<='Z')) { if(s[i]>='A'&&s[i]<='Z') { s_argument.push_back(s[i]-'A'+'a'); } else s_argument.push_back(s[i]); s_argument.push_back('#'); } } if(s_argument.length()==1)return true; for(int i=s_argument.length()/2-1;i>=0;i--) { if(s_argument[i]!=s_argument[s_argument.length()-1-i])return false; } return true; } };