Recursive Tree

A recursive tree, in the context of recursion, is a visual representation of how recursive function calls are stacked on top of each other. It's essentially a tree-like structure where each node represents a function call, and child nodes represent subsequent function calls made within that function.

Let's take an example of a simple recursive function to calculate the factorial of a number:

#include <iostream>
using namespace std;

int factorial(int n) {
    if (n == 0 || n == 1) {
        return 1;
    } else {
        return n * factorial(n - 1);
    }
}

int main() {
    int result = factorial(5);
    cout << "Factorial of 5 is: " << result << endl;
    return 0;
}

When factorial(5) is called, a sequence of function calls is made:

factorial(5)
    ↓
5 * factorial(4)
          ↓
      4 * factorial(3)
               ↓
           3 * factorial(2)
                    ↓
                2 * factorial(1)
                         ↓
                         1

This sequence of function calls forms a tree-like structure, where each function call is a node, and each subsequent function call is a child node. This structure is called a recursive tree.