The stack frames also provide a scope for the variables used by the function. In the case of linked lists, we will see that recursive algorithms are almost always shorter and simpler, once you are comfortable with the notion of recursion. Think of the return value on the stack taking the place of an accumulator variable. Recursive Definition of a Linked List The power of recursive algorithms becomes most obvious when they are applied to data structures which are themselves recursive. In this way, the C++ call stack takes the place of the stack we used explicitly in Listing 4. This return value is then used in place of the function call ( toStr(1,2)) in theĮxpression '1' + convertString, which will leave the string '10' on the top of the stack. Notice that the call to toStr(2//2,2) leaves a return value of Figure 6 illustrates the call stack after the return statement on line 4.įigure 6: Call Stack Generated from toStr(10,2) When the function returns, the return value is left on top of the stack for the calling function to access. To use recursion, you generally want algorithm to use stack space k log N or something like that (examples, merge sort or quick sort).

Recursing through linked list uses stack space k N, where N is list length (unless using language which quarantees tail recursion). When a function is called in Python, a stackįrame is allocated to handle the local variables of the function. Yeah, with recursion, you always need to consider iteration depth. The previous example gives us some insight into how C++ implements a recursive function call. Notice that now we can simply pop the characters off the stack and concatenate them into the final result, '1010'.įigure 5: Strings Placed on the Stack During Conversion Returning to the previous example we can see that after the fourth call to toStr the stack would look like Figure 5. Converting an Integer to a String Using a Stack (lst_recstackpy)Įach time we make a call to toStr, we push a character on the stack.

Recursive linked list stack