What is Recursive Permutation in C++? [Algorithm and Source Code]

A full permutation is list of all variation for given items (usually numbers). For example, the full permutation of 3 elements are:

1 2 3
1 3 2
2 1 3
2 3 1
3 1 2
3 2 1

Also Read: C program to find factorial of any number using recursion
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As we can easily calculate, the total number of iterations is n! (factorial). How do we get this number? The most simple way is to think of the number of different items we can choose for each position. For example, for the first place, we have n choices, and we have n-1 choices for the second place, and etc. Thus we have n*(n-1)*(n-2)*…1 that gives a total number n!.

So how to emulate this for the whole process? First, we can define a recursive function that ends printing one solution by checking if we have reached the end. For each iteration, we can simply swap the current item with the rest of the items and try the next position recursive. As we use a global array variable nums to keep the items, we need to swap the items back after each recursion call. The source code is pretty straight forward. Open Visual Studio, choose the ‘Console Application’ from ‘C++’ language projects.