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  1. Prepare
  2. Algorithms
  3. Strings
  4. Palindrome Index
  5. Discussions

Palindrome Index

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1094 Discussions

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  • alban_tyrex
     + 0 comments

    Here is my c++ solution : explanation here https://youtu.be/QjHpvMdfnqs,

     bool isPalindrome(string s){
     string r = s;
     reverse(r.begin(), r.end());
     return s == r;
 }

int palindromeIndex(string input) {
    int s, e;
    for(s = 0, e = input.size() - 1; s < e; s++, e--){
        if(input[s] != input[e]) break;
    }
    if(s >= e) return -1;
    string s1 = input, s2 = input;
    s1.erase(s1.begin() + s);
    if(isPalindrome(s1)) return s;
    s2.erase(s2.begin() + e);
    if(isPalindrome(s2)) return e;
    return -1;
}

  • saminazubair93
     + 0 comments

    Here is my solution in PHP

    s); arr); arr); res);

       `$resCount = count($`res);
   $result = -1;
   if($resCount == 1)
   {
    $result = -1;
   }
   else if(`$resCount == $`arrSum)
   {
    $result = -1;
   }
   else if(`$arr == $`arrRev)
   {
     $result = -1;
   }
   else
   {
    $equal = 'yes';
    $oddPair = '';
    $min = 0;
    foreach (`$res as $`key => $value) {
          if($value%2 !==0)
          {
            $equal = 'no';
            `$oddPair = $`key;
            if(`$value <$`min)
            {
               `$min = $`value; 
                `$oddPair = $`key;
            }


          }
    }
    `$len = count($`arr);

    if ($equal == 'no') {

         $findIndex = '';
         for (`$i=0; $`i < `$len ; $`i++) { 
               if(`$arr[$`i] == $oddPair)
               {

                 `$string = implode('', $`arr);

                       `$part1 = substr($`string, 0,$i);
                       `$part2 = substr($`string,`$i+1,$`len-1);


                     `$str1 = $`part1.$part2;

                     `$str2 = strrev($`str1);

                     if(`$str1 === $`str2)
                     {

                        `$findIndex =$`i;
                        break;
                     }

               }


         }
         `$result = $`findIndex;
    }

   }
   return $result;

  • gsharew
     + 0 comments

    How is this easy ? WTF

  • ahmedkhalilalsa1
     + 0 comments
    by C:
int palindromeIndex(char* s) {

    int len=0, left=0, right=len-1, tempLeft=0, tempRight=len-1;
    if(s != NULL) {
        while(s[len]!='\0') len++;
        right=len-1;
        tempRight=len-1;

        // normal checking
        while(left<right && (s[left]==s[right])) {
            left++;
            right--;
        }
        if(left>=right) return -1;

        // try to skip left
        tempLeft = left++;
        tempRight = right;
        while(left<right &&(s[left]==s[right])) {
            left++;
            right--;
        }
        if(left>=right) return tempLeft;

        // try to skip right ,BUT need first to back to the old value
        left = tempLeft;
        right = tempRight-1;
        while(left<right && (s[left]==s[right])) {
            left++;
            right--;
        }
        if(left>=right) return tempRight;
        else
            return -1; // so no solution for this string

    } else {
        return -1;
    }


}

  • highsoft_soi
     + 0 comments

    Perl solution:

    sub is_palindrome {
    my ($st, $left_s, $right_s) = @_;
    while ($left_s < $right_s) {
        return 0 if substr($st, $left_s, 1) ne substr($st, $right_s, 1);
        $left_s++;
        $right_s--;
    }
    return 1;
}

sub palindromeIndex {
    my $s = shift;
    my $left_side = 0;
    my $right_side = length($s) - 1;

    while ($left_side < $right_side) {
        if (substr($s, $left_side, 1) ne substr($s, $right_side, 1)) {
            if (is_palindrome($s, $left_side + 1, $right_side)) {
                return $left_side;
            } elsif (is_palindrome($s, $left_side, $right_side - 1)) {
                return $right_side;
            } else {
                return -1;
            }
        }
        $left_side++;
        $right_side--;
    }
    return -1;
}