Recursive functions in C ++: examples

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Recursive functions in C ++: examples

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I'm starting to learn in C ++ and, for the moment, I look at recursive functions. I have already seen some interesting examples, such as calculating the factorial of a number, but I would like to see other examples. I hope you do not consider this question too broad. It is just a matter of seeing and sharing other examples that may be helpful to those learning the language. Thanks!

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asked by anonymous 11.12.2015 / 02:07

1 answer

R-Studio - Error installing package WEBAPI AND CERTIFICATE A3 - TOKEN

score 1 · Answer 1

Here is a program I wrote some time ago to teach functions, in particular to exemplify the difference between normal (using an iterative algorithm) and recursive functions. In this case, it is intended to calculate the values of the Fibonnaci sequence (see here for example).

/*
 *       Sequência de Fibonacci  
 *       (de forma normal e de forma recursiva; esta última é bem mais lenta)
 *
 */


#include <iostream>
using namespace std;

unsigned long long fibonacci(const unsigned int n){
    unsigned long long resultado;
    if (n==0)
        resultado=0;
    else if (n==1)
        resultado=1;
        else{
            unsigned long long tabela[n+1];
            tabela[0]=0;
            tabela[1]=1;
            for (auto i=2;i<=n;++i){
                tabela[i]=tabela[i-2]+tabela[i-1];
            }
            resultado=tabela[n];
        }           
    return resultado;
}

unsigned long long fibonacciRecursive(const unsigned int n){
    if (n==0)
        return 0;
    else if (n==1)
         return 1;
        else
            return(fibonacciRecursive(n-2)+fibonacciRecursive(n-1));
}


int main(){
    unsigned int numero;

    do{
        cout << "Escolha numero (0 para terminar): ";
        cin >> numero;
        cout << "O numero de fibonnaci de ordem " << numero << " e " << fibonacci(numero) << endl;
        cout << "O numero de fibonnaci de ordem " << numero << " e " << fibonacciRecursive(numero) << endl;
        cout << endl;
    }while(numero!=0);

    return 0;
}