Lecture 53:- Indirect Recursion

Indirect recursion, also known as mutual recursion, refers to a situation where two or more functions call each other in a cyclical manner, either directly or indirectly. In indirect recursion, the functions form a cycle of dependencies, with each function relying on the other(s) to complete its execution.

Here's an example of indirect recursion in C++:

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// Forward declaration of functions void functionA(int n);  // Function A void functionB(int n);  // Function B void functionA(int n) {    if (n > 0) {        printf("Function A: %d\n", n);        functionB(n - 1);  // Call function B    } } void functionB(int n) {    if (n > 0) {        printf("Function B: %d\n", n);        functionA(n - 1);  // Call function A    } } int main() {    functionA(5);    return 0; }

In this example, we have two functions, functionA and functionB, that call each other indirectly. Each function prints its value and then calls the other function with a decremented value. This creates a cyclical dependency between the two functions, resulting in a series of alternating function calls.

When executed, the program will output:

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Function A: 5 Function B: 4 Function A: 3 Function B: 2 Function A: 1

Note that in this specific example, the functions terminate based on a condition (n > 0). Without such conditions, the recursive calls would continue indefinitely, leading to an infinite loop.

Indirect recursion can be useful in situations where multiple functions need to collaborate or work together to solve a problem. By delegating specific tasks to different functions and allowing them to call each other, complex computations can be broken down into more manageable parts.

However, when working with indirect recursion, it's important to ensure that there are appropriate termination conditions in place to avoid infinite loops. Also, the order in which the functions are called and the relationship between their dependencies should be carefully considered to ensure correct and desired behavior.