Program which employs recursion

Recursion makes program elegant. However, if performance is vital, use loops instead as recursion is usually much slower. That being said, recursion is an important concept.

It is frequently used in data structure and algorithms. For example, it is common to use recursion in problems such as tree traversal.

Course Index Explore Programiz. Popular Tutorials Data Types in C. C for Loop. Arrays in C Programming. Pointers in C. Find roots of a quadratic equation. This is because, inside fibo function, there is a statement which calls fibo function again directly. A function is said to be indirect recursive if it calls another function and this new function calls the first calling function again. In this program, func1 calls func2 , which is a new function.

But this new function func2 calls the first calling function, func1 , again. Since all the variables and other stuff declared inside function get stored in the stack, therefore a separate stack is maintained at each recursive call.

Once the value is returned from the corresponding function, the stack gets destroyed. Recursion involves so much complexity in resolving and tracking the values at each recursive call. Therefore we need to maintain the stack and track the values of the variables defined in the stack. Let us consider the following example to understand the memory allocation of the recursive functions.

First, all the stacks are maintained which prints the corresponding value of n until n becomes 0, Once the termination condition is reached, the stacks get destroyed one by one by returning 0 to its calling stack. Consider the following image for more information regarding the stack trace for the recursive functions. JavaTpoint offers too many high quality services. Mail us on [email protected] , to get more information about given services.

Please mail your requirement at [email protected] Duration: 1 week to 2 week. Command Line Arguments. Enter the number whose factorial you want to calculate?

Next Topic Storage classes in C. Reinforcement Learning. R Programming. So fib 3 will be called and evaluated two times completely independently. We can clearly notice that fib 3 is evaluated two times and fib 2 is evaluated three times. We can optimize that by remembering already-evaluated values: if a value of say fib 3 is calculated once, then we can just reuse it in future computations. Instead of going from n down to lower values, we can make a loop that starts from 1 and 2 , then gets fib 3 as their sum, then fib 4 as the sum of two previous values, then fib 5 and goes up and up, till it gets to the needed value.

On each step we only need to remember two previous values. The approach is called dynamic programming bottom-up. Please note that we use a temporary variable tmp to walk over the list. Technically, we could use a function parameter list instead:.

In the future we may need to extend a function, do something else with the list. If we change list , then we lose such ability. Talking about good variable names, list here is the list itself. The first element of it. And it should remain like that. From the other side, the role of tmp is exclusively a list traversal, like i in the for loop. The recursive variant of printList list follows a simple logic: to output a list we should output the current element list , then do the same for list.

Technically, the loop is more effective. These two variants do the same, but the loop does not spend resources for nested function calls. Output a single-linked list from the previous task Output a single-linked list in the reverse order. So what we can do is to first go through the items in the direct order and remember them in an array, and then output what we remembered in the reverse order:.

Please note that the recursive solution actually does exactly the same: it follows the list, remembers the items in the chain of nested calls in the execution context stack , and then outputs them. We want to make this open-source project available for people all around the world. Tutorial map. Our first topic will be recursion. If you are not new to programming, then it is probably familiar and you could skip this chapter. Recursion is usually shorter. A recursive solution is usually shorter than an iterative one.

Please note:. Tasks Sum all numbers till the given one. The solution using a loop:. Calculate factorial. We can write a definition of factorial like this: n! By definition, a factorial n! Fibonacci numbers. Write a function fib n that returns the n-th Fibonacci number.