String Suffix and Prefix. Take a piece that serves both

Question

I need to do a function that returns the Length of a part of the string that is both suffix and prefix. So: Given the string: abbabba, the answer would be 4, because that would be:

Prefix:

a ab abb abba abbab abbabb 

Suffix:

a ba bba abba babba bbabba

Logo Abba is both prefix and suffix. How do I do this?

I started like this and I can’t and I only have 10 more minutes.

public int teste(string nome)
        {

            string[] pre = new string[nome.Length];
            string[] suf = new string[nome.Length];

            for (int i = 0; i < nome.Length - 1; i++)
            {
                pre = nome[i].ToString();// Erro aqui
            }

        }

Answer 1

I made a while that compares the beginning with the end until reaching the middle

String nome = "abbabba";

var i = 0; // começo
var j = nome.Length-1; // fim, -1 porque começo do 0
var tamanho = 0;
var sufixoEprefixo = "";

while (i <= j) {
    if (nome[i] == nome[j]) { // mesmo caracter
        tamanho++;
        sufixoEprefixo += nome[i];
    } else { // se for diferente pode parar 
        break;
    }
    i++; // avança letra
    j--; // retrocede letra
}
Console.WriteLine(tamanho);
Console.WriteLine(sufixoEprefixo);

4

Abba

Ideone Exemplo

Answer 2

I don’t know what the code in C would look like, but let’s take it step by step:

1 Pass string to function
2 Declare 1 array for prefixes and 1 array for suffixes
3 Declare 1 variable to count how many prefixes are equal to suffixes
4 fill in the prefix array
5 fill the suffix array
6 for each element in the prefix array, check that it is in the suffix array
   6.1 if you are, add 1 to your variable
7 return the variable

NOTE: You will not match the array to a string, you will add the string to the array.

Answer 3

I don’t know how it looks in C#,but I’ll give you the answer in with logic and you can apply it in your case.

var String = "abbabba";
var len = String.length; //Aqui você terá o tamanho da sua string
var array1, array2;
var lenfinal;


para(i=1;i<=len;i++){
    array1[i] = String.caracter(0,i);
    array2[len-i] = String.caracter(len-i,i);
}

//Nesse ponto você deveria ter 2 arrays(array1 e array2) com todos os prefixos e sufixos da string

para(u=0;u<len;u++) {
    if(array1[u] estacontidoem array2){
        lenfinal = array[u].length;
    }
}

imprime(lenfinal);

That’s basically it, just apply in C# now

In this case I believe that the correct answer would be 7. Because we have a palindrome the whole word can be suffix and prefix at the same time