Problem_STOII_0018_isPalindrome.cc

#include <iostream>
#include <vector>

using namespace std;

// seem as leetcode 0125
// https://leetcode.cn/problems/valid-palindrome/
// see at Problem_0125_isPalindrome.cc
class Solution
{
 public:
  bool validChar(char c) { return std::isalpha(c) || std::isdigit(c); }

  bool isEuqal(char c1, char c2) { return (c1 == c2) || ((c1 ^ 32) == c2); }

  bool isPalindrome(string s)
  {
    if (s.length() == 0)
    {
      return true;
    }
    int l = 0;
    int r = s.length() - 1;
    while (l <= r)
    {
      if (validChar(s[l]) && validChar(s[r]))
      {
        if (!isEuqal(s[l], s[r]))
        {
          return false;
        }
        l++;
        r--;
      }
      else
      {
        l += validChar(s[l]) ? 0 : 1;
        r -= validChar(s[r]) ? 0 : 1;
      }
    }
    return true;
  }
};