N Coin Change

http://www.geeksforgeeks.org/dynamic-programming-set-7-coin-change/

We want to make change for N cents. and we have an infinite supply of set of coins. How many ways can we make the change to get N?

m is the size of the elements within set
n is the sum we are trying to achieve
int count(int set[], int m, int n) {
    // there is one way to achieve
    // when sum is 0: which is 0 coins
    if(n ==  0)
     return 1;

    if(n < 0)
     return 0;

     // if we have no elements within the
     // array and n is greater than or equal o
     // one, then there is no way to reach n, so
     // we return 0
    if(m <= 0 && n >= 1)
     return 0;

    // first part includes set[m - 1]
    // second part excludes set[m - 1]
    return count(set, m - 1, n) + count(set, m, n - set[m - 1]);
}