Counting Sort

#include <iostream>
#include <vector>
#include <algorithm>
#include <ctime>

using namespace std;

void countingSort(const vector<int> &a, vector<int> &b)//-> include <vector>;
{
    int k = *max_element(a.begin(), a.end());//-> include <algorithm>;
    k++;

    vector<int> c(k);

    for (int i = 0; i < a.size(); i++)
        c[ a[i] ]++;
    for (int i = 1; i < k; i++)
        c[i] += c[i - 1];

    for (int i = (a.size() - 1); i >= 0; i--)
    {
        b[ c[ a[i] ] - 1 ] = a[i];
        c[ a[i] ]--;
    };
};

int main()
{
    system("COLOR F0");
    srand( time(NULL) );//-> include <ctime>

    vector<int> a;
    for (int i = 0; i < 5; i++)
    {
        int num = rand()% 30 + 1;//-> from 1 to 30;
        a.push_back(num);
    };

    vector<int> b(a.size());

    for (int i = 0; i < a.size(); i++)
        cout << " a [ " << i << " ]\t= " << a[i] << endl;
    cout << endl;

    countingSort(a, b);

    for (int i = 0; i < b.size(); i++)
        cout << " b [ " << i << " ]\t= " << b[i] << endl;
    cout << endl;

    system("PAUSE");
    return (0);
};