coin_change.cpp

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

/*
 * Complete the 'getWays' function below.
 *
 * The function is expected to return a LONG_INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. LONG_INTEGER_ARRAY c
 */

long getWays(int n, vector<long> c)
{
    long ways[n+1];
    memset(ways, 0, (n+1)*sizeof(long));
    ways[0] = 0;

    sort(c.begin(), c.end());

    for(int i=0;i<c.size();i++)
	ways[c[i]]++;
    
    for (int i=1; i<=n; i++)
    {
	ways[i] += ways[c[0]]*ways[i-c[0]];
    }

    cout << ways[n] << "\n";

    return ways[n];
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string first_multiple_input_temp;
    getline(cin, first_multiple_input_temp);

    vector<string> first_multiple_input = split(rtrim(first_multiple_input_temp));

    int n = stoi(first_multiple_input[0]);

    int m = stoi(first_multiple_input[1]);

    string c_temp_temp;
    getline(cin, c_temp_temp);

    vector<string> c_temp = split(rtrim(c_temp_temp));

    vector<long> c(m);

    for (int i = 0; i < m; i++) {
        long c_item = stol(c_temp[i]);

        c[i] = c_item;
    }

    // Print the number of ways of making change for 'n' units using coins having the values given by 'c'

    long ways = getWays(n, c);

    fout << ways << "\n";

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
	);

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
	);

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}