?LeetCode刷題實(shí)戰(zhàn)125：驗(yàn)證回文串
Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For the purpose of this problem, we define empty string as valid palindrome.
題意
示例 1:
輸入: "A man, a plan, a canal: Panama"
輸出: true
示例 2:
輸入: "race a car"
輸出: false
解題
public boolean isPalindrome(String s) {
???if?(s.isEmpty())
???????return?true;
???int begin?= 0;
???int end?= s.length() - 1;
???char beginChar, endChar;
???while?(begin?<= end){
???????beginChar = s.charAt(begin);
???????endChar = s.charAt(end);
???????if?(!Character.isLetterOrDigit(beginChar)){
???????????begin++;
???????????continue;
???????}
???????else?if?(!Character.isLetterOrDigit(endChar)){
???????????end--;
???????????continue;
???????}
???????else?{
???????????if?(Character.toLowerCase(beginChar) != Character.toLowerCase(endChar))
???????????????return?false;
???????????else{
???????????????begin++;
???????????????end--;
???????????}
???????}
???}
???return?true;
}