#pragma once
#include<iostream>
#include<cstring>
using namespace std;

void our_swap(auto& a, auto& b){
	char temp[sizeof(a)];
	memcpy(temp, &a, sizeof(a));
	memcpy(&a, &b, sizeof(a));
	memcpy(&b, temp, sizeof(a));
}

void bubble_sort(auto& array, size_t length){
	bool sorted = false;
	while(!sorted){  
		sorted = true;
		for(size_t i = 0; i < length - 1; i++){ // O(n)
			if(array[i] > array[i+1]){
				our_swap(array[i], array[i+1]);
				sorted = false;
			}
		}
	}
}

void selection_sort(auto& array, size_t length){
	size_t index_of_best_front = 0;
	for(size_t done_index = 0; done_index < length - 1; done_index++){
		index_of_best_front = done_index;
		for(size_t i = done_index + 1; i < length; i++)
			if(array[index_of_best_front] > array[i])
				index_of_best_front = i;
		if(done_index != index_of_best_front)	
			our_swap(array[done_index], array[index_of_best_front]);
	}
}

void quicksort(auto* array, size_t length){
	// Step 0:  If the array is short, just use selection sort
	if(length <= 1)
		return;
	if(length < 5) {
		selection_sort(array, length);
		return;
	}

	// Step 1:  choose pivot
	if(array[0] > array[length - 1])
		our_swap(array[0], array[length - 1]);
	if(array[length / 2] > array[length - 1])
		our_swap(array[length - 1], array[length / 2]);
	if(array[0] > array[length/2])
		swap(array[length-1], array[0]);
	else
		swap(array[length-1], array[length/2]);

	// Step 2:  Categorize items as less than or greater than the pivot
	size_t b = 0, e = length - 2, median;
	while(true){
		for(; array[length - 1] > array[b]; b++);
		for(; array[e] > array[length - 1]; e--);
		if(e > b) {
			our_swap(array[b], array[e]);
			e--;
			b++;
		}
		else {
			median = b;
			break;
		}
	}

	// Step 3:  Move the pivot back where it goes
	our_swap(array[median], array[length - 1]);
	// Step 4:  Call quicksort on each half
	if(median)
		quicksort(array, median );
	if(length - median)
		quicksort(array + median + 1, length - median - 1);
}