[Leetcode 125] Valid palindrome

Source: Internet
Author: User
Tags alphanumeric characters

https://leetcode.com/problems/valid-palindrome/

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:
Are you consider that the string might is empty? This was a good question to ask during a interview.

For the purpose of this problem, we define empty string as valid palindrome.

This question is more conventional, the idea is also very simple, is two pointers. One pointer points to the beginning of the string, and the other pointer to the end of the string. Use the while loop to ignore non-alphanumeric characters. Look at the following code:

Class Solution {public:    bool Ispalindrome (string s) {        string::const_iterator = S.cbegin ();        String::const_iterator right = S.cend ()-1;                while (left < right) {                        //ignores non-alphanumeric characters while             (left < right &&!isalnum (*left)) {left                ++;            }            while (left < right &&!isalnum (*right)) {                right--;            }                        if (ToLower (*left)! = ToLower (*right)) {                return false;            } else {                left++;                right--;            }        }                return true;            }};

[Leetcode 125] Valid palindrome

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.