Skip to main content


Showing posts from January, 2009

Use of Memoization in Recursion

Memoization can be used to reduce function calls or computations. In the following example of Fibonacci series generation through C++, I will use normal recursion and then will change the same for memoization( ) to show the reduction of the function call. This is a simple demo implementation. static int counter = 0; int normalfibrecursion(int n) { if( n < 1) { return 0; } if(n == 1) { return 1; } if(n < 3) { return 1; } else { cout << "Call normalfibrecursion(" << n-2 << ") and normalfibrecursion(" << n-1 << ")\n"; counter++; return normalfibrecursion(n-2) + normalfibrecursion(n-1); } } In the above-mentioned simple prototype implementation for the Fibonacci series of n=10, the total function call comes to (54*2) times. This is usually very high and it will grow exponentially as n increases. Below mentioned picture demonstrates the fact: USE OF MEM

Generic Swap without using template

The idea behind this was, I wanted to write a function that will take two parameters of the same type as a parameter and then it will swap them. It is a kind of generic swap but without the use of a C++ template. So the best way of doing it using "void *" as a parameter. As we know "void *" represents any arbitrary type that actually eases my job of writing a generic swap function. So, the function signature can be like below: void swap(void *arg1, void *arg2); "void *" points to the starting address of the arbitrary location in the memory, irrespective of the bit pattern. Try to write the function like the below: void swap(void *arg1, void *arg2) { void temp = *arg1; arg1 = *arg2; *arg = temp; } Oops, this is full of errors. 1. We can't declare a variable of type "void". 2. "void *" can't be dereferenced. 3. We also interested in swapping values. So, number of bytes making up the values to be pass