{"id":929,"date":"2020-06-11T10:15:01","date_gmt":"2020-06-11T10:15:01","guid":{"rendered":"https:\/\/blog.prepbytes.com\/?p=929"},"modified":"2023-07-24T07:39:26","modified_gmt":"2023-07-24T07:39:26","slug":"minimum-number-of-operations-to-make-string-palindrome","status":"publish","type":"post","link":"https:\/\/prepbytes.com\/blog\/minimum-number-of-operations-to-make-string-palindrome\/","title":{"rendered":"Minimum Number of Operations to Make String Palindrome"},"content":{"rendered":"

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Palindrome string is a string which is the same on reading from the front side as well as on the rear side. Example of a palindrome string is \u201cNAMAN\u201d as we can see that on reading this string from both ends, we will get \u201cNAMAN\u201d as our output. Hence, the given string will be a palindrome string. From analyzing single characters to rearranging entire sequences, we will unravel diverse methodologies for crafting palindromes efficiently. These methods not only demonstrate the beauty of problem-solving in computer science but also hold practical implications in various real-world applications, including string manipulation, error correction, and data validation.<\/p>\n

Minimum Number of Moves to Make Palindrome String<\/h2>\n

Given a string, you have to find the minimum number of moves to make palindrome string i.e. you have to change the ascii value of the character which is present in the string. Palindrome string is a string which is same after reversing it. You can Practice this Question, for understanding the concept to find minimum number of moves to make palindrome string.<\/p>\n

String Palindrome Test Case<\/h2>\n
Input:\n1\nabcd\n\nOutput:\n4\n\nExplanation:\nString 'abcd' can be converted into its palindrome if we convert : \n\n'a'->'d' or 'd'->'a'  which takes (ASCII(d) - ASCII(a)) steps i.e. 3 steps.\n\n'b'->'c' or 'c'->'b' which takes (ASCII(b) - ASCII(c)) steps i.e. 1 step.\n\nHence the total number of steps is 4.<\/code><\/pre>\n
How to find number of moves to make palindrome?<\/h2>\n
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1) Palindrome<\/strong>: A palindrome is a string<\/a> that contains same characters from both ends. For example, nitin<\/code> can be read same from both ends. Element at i<\/code>th<\/sup> index from the start and end side both are the same.<\/p>\n
2) As we know palindromes contains same characters at i<\/code>th<\/sup> index and  (len -i)<\/code>th<\/sup> index. So we iterate from 0 to middle of the string and compare all the characters if at some index characters are different, the string is not palindrome<\/em><\/strong>. If all the characters remain same, the string is palindrome<\/em><\/strong>.<\/p>\n
3) If two characters are not same at i<\/code>th<\/sup> index and  (len -i)<\/code>th<\/sup> index, we have to make them the same. We can make them same by adding the ASCII value of difference of both the character to the smaller character.<\/p>\n
4) Finally we add the difference to our counter, the final value of the counter will be answer according to the fundamentals of data structures in c++.<\/p>\n<\/blockquote>\n
Example: Number of moves to make palindrome<\/h3>\n
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  • Let’s assume given string is abcds<\/code> and we check values from both ends one by one, and check their difference, we take positive difference value as our step<\/code>.<\/li>\n
  • In<\/em><\/strong> 1<\/code>st<\/sup> iteration<\/em><\/strong>, we compare a<\/code> from start and s<\/code> from end, we can convert either a<\/code> to s<\/code> or s<\/code> to a<\/code>. Their ASCII value difference is 18<\/code>, so our current step count is 18<\/code>.<\/li>\n
  • In<\/em><\/strong> 2<\/code>nd<\/sup> iteration<\/em><\/strong>, we compare b<\/code> from start and d<\/code> from end, we can convert either b<\/code> to d<\/code> or d<\/code> to b<\/code>. Their ASCII value difference is 2<\/code>, so our current step count is 20<\/code>.<\/li>\n
  • As last element left is middle element,which is also a palindrome in it’s own, so we’ll skip that. Hence We get our final count as 20<\/code>.<\/li>\n<\/ul>\n<\/blockquote>\n
    Solution to find minimum number of moves to make palindrome:<\/h2>\n\t\t\t\t\t\t