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Write a function that returns the longest palindrome in a given string

I have a C++ assignment which wants me write a program that finds the longest palindrome in a given text. For example, the text is this: asdqerderdiedasqwertunut, my program should find tunut in the index of 19. However if input is changed into this astunutsaderdiedasqwertunutit should find astunutsa in the index of 0 instead of tunutin index of 22.

So, my problem is this. But I am a beginner at the subject, i know just string class, loops, ifs. It would be great if you could help me on this.

Thanks in advance.

Answer 1

The idea is very simple:

• Write a function is_palindrome(string) that takes a string, and returns true if it is a palindrome and false if it is not
• With that function in hand, write two nested loops cutting out different substrings from the original string. Pass each substring to is_palindrome(string), and pick the longest one among the strings returning true.

You can further optimize your program by examining longest substrings ahead of shorter ones. If you examine substrings from longest to shortest, you’ll be able to return as soon as you find the first palindrome.