125. Valid Palindrome (Array; Two-Pointers)

標籤：

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.

class Solution {public:    bool isPalindrome(string s) {        if(s.empty()) return true;        int sLength = s.length();        int front = -1;        int rear = sLength;        char cFront;        char cRear;        while (1)        {                cFront = s[++front];                cRear = s[--rear];                if(front > rear) break;                if(cFront <= ‘Z‘&& cFront >=‘A‘)                {                    cFront +=32;                }                if(cRear <= ‘Z‘&& cRear >=‘A‘)                {                    cRear +=32;                }                              while(  cFront < ‘0‘ || (cFront < ‘a‘ && cFront > ‘9‘)|| cFront>‘z‘)                {                    cFront = s[++front];                    if(front >= rear) break;                    if(cFront <= ‘Z‘&& cFront >=‘A‘)                    {                        cFront +=32;                    }                }               while(  cRear < ‘0‘ || (cRear < ‘a‘ && cRear > ‘9‘)|| cRear>‘z‘)                {                    cRear = s[--rear];                    if(front >= rear) break;                    if(cRear <= ‘Z‘&& cRear >=‘A‘)                   {                       cRear +=32;                    }                }                            if(front >= rear) break;                if(cFront!=cRear)                {                    return false;                }            }            return true;    }};

 

125. Valid Palindrome (Array; Two-Pointers)