Question

C++ program

checks if an input string is a palindrome or not. Ignore case and remove all non-alphanumeric characters in the input string.

C++ program uses only one string (no extra-string or array). And also, use two indices to point from the beginning and ending positions.

Sample Input 0

Race car

Sample Output 0

TRUE

Sample Input 1

7...8 Don't nod 78.

Sample Output 1

FALSE

Answer 1

#include<iostream>

using namespace std;

bool isPalindrome(string s){
   int i,j;
   for(i = 0; s[i]!='\0'; i++){
      s[i] = tolower(s[i]);
   }
   
   string alphaNum = "";
   for(i = 0;s[i]!='\0';i++){
      if((s[i]>='a' && s[i]<='z') || (s[i]>='0' && s[i]<='9'))
         alphaNum += s[i];
   }
   i = 0;
   j = alphaNum.length()-1;
   while(i<j){
      if(alphaNum[i] != alphaNum[j]){
         return false;
      }
      i++;
      j--;
   }
   return true;
}



int main()
{
   string str;
   getline(cin,str);
   if(isPalindrome(str)){
      cout<<"TRUE"<<endl;
   }
   else{
      cout<<"FALSE"<<endl;
   }
   return 0;
}