Leetcode 125. Valid palindrome

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.

• String problem. Two methods, one is to directly compare string flip, the other is the traditional two pointer movement comparison.
• Learned the string-related STL algorithms and functions, adding char to a string with push_back.
• Toupper-c++ Reference
  • http://www.cplusplus.com/reference/cctype/toupper/
• Isalnum-c++ Reference
  • Http://www.cplusplus.com/reference/cctype/isalnum/?kw=isalnum
• Transform-c++ Reference
  • Http://www.cplusplus.com/reference/algorithm/transform/?kw=transform
• String::p ush_back-c++ Reference
  • http://www.cplusplus.com/reference/string/string/push_back/
• Reverse_copy-c++ Reference
  • http://www.cplusplus.com/reference/algorithm/reverse_copy/
• Reverse_copy
  • Https://msdn.microsoft.com/zh-cn/library/c7ty5c36.aspx

1#include <iostream>2#include <string>3#include <cctype>//ToUpper, Isalnum4#include <algorithm>//Transform5 using namespacestd;6 7 classSolution {8  Public:9     BOOLIspalindrome (strings)Ten     { One          stringStemp ="", Sreverse =""; A  -          //Convert characters to UPPER - transform (S.begin (), S.end (), S.begin (),:: ToUpper); the  -          //considering only alphanumeric characters -           for(inti =0; I < s.length (); i + +) -              if(Isalnum (s.at (i))) +Stemp.push_back (s.at (i));//appends character to the end of the string, increasing it length by one. -  +          //need to allocate space if use reverse_copy A sreverse.resize (Stemp.length ()); at reverse_copy (Stemp.begin (), Stemp.end (), Sreverse.begin ()); - /* - sreverse = stemp; - Reverse (Sreverse.begin (), Sreverse.end ()); - */          - /* in cout << stemp << Endl; - cout << sreverse << Endl; to */          +          returnStemp = =Sreverse; -     } the      *     BOOLIsPalindrome2 (strings) $     {Panax Notoginseng          intStart =0, end = S.length ()-1; -  the           while(Start <end) +          { A                if( !isalnum (s.at (start))) theStart + +; +                Else if( !isalnum (s.at (end))) -End--; $                Else if(ToUpper (s.at (start))! = ToUpper (s.at (end)))//Remember ToUpper $                       return false; -                Else -                { the                    //Remember to move ptr -Start + +;WuyiEnd--; the                } -          } Wu           -          return true; About     } $      - }; -  - intMain () A { + solution testsolution; the     stringStest[] = {"a man, a plan, a Canal:panama","Race a car"}; -      $      for(inti =0; I <2; i + +) thecout << testsolution.ispalindrome (stest[i]) <<Endl; the      the GetChar (); the      -     return 0; in}

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Leetcode 125. Valid palindrome