/**
 * Clayton Cafiero
 * CS 2240
 * 05-Jan-2021
 */

#include <vector>
#include <iostream>


template<typename Comparable>
void printVector(const std::vector<Comparable>& v) {
    for (Comparable item : v) {
        std::cout << item << " ";
    }
    std::cout << std::endl;
}

/**
 * Quicksort stable, recursive. This implementation of Quicksort
 * is stable, but requires more space. Note we have the vectors
 * smaller, equal, and larger.
 */
template<typename Comparable>
void quicksortStable(std::vector<Comparable>& v) {
    // Recursive base case
    if (v.size() < 2) {
        return;
    }
    Comparable pivot = v[0];
    std::vector<Comparable> smaller, equal, larger;
    int i;  // OK to declare here. See where we copy values back to orig. vector
    for (i = 0; i < v.size(); ++i) {
        if (v[i] < pivot) {
            smaller.push_back(v[i]);
        } else if (v[i] > pivot) {
            larger.push_back(v[i]);
        } else {
            equal.push_back(v[i]);
        }
    }

    quicksortStable(smaller);
    quicksortStable(larger);

    // Copy everything back into vector
    for (i = 0; i < smaller.size(); ++i) {
        v[i] = smaller[i];
    }
    // Omit initialization of i and continue...
    for (; i < smaller.size() + equal.size(); ++i) {
        v[i] = equal[i - smaller.size()];
    }
    // Omit initialization of i and continue...
    for (; i < v.size(); ++i) {
        v[i] = larger[i - smaller.size() - equal.size()];
    }
}

int main() {

    std::vector<int> v = {8, 5, 0, 4, 3, 9, 1, 7, 2, 6};

    printVector(v);
    quicksortStable(v);
    printVector(v);

}