排序算法

1. 建堆

#include <stdio.h>

void swap(int *a, int *b);
//維護堆的性質
void AdjustHeap(int a[], int heap_size, int i)
{
	int left = 2 * i + 1;
	int right = left + 1;
	//if (i == 0) {
		//left = 1;
		//right = 2;
	//}
	int largest = i;
	if (left < heap_size && a[left] > a[i])
		largest = left;
	if (right < heap_size && a[right] > a[largest])
		largest = right;
	if (largest != i) {
		swap(&a[largest], &a[i]);
		AdjustHeap(a, heap_size, largest);
	}
}

void swap(int *a, int *b)
{
	int tmp = *a;
	*a = *b;
	*b = tmp;
}
//堆排序
void heap_sort(int arr[], int heap_size) {
	int i;
	for(i = heap_size-1; i > 0; --i) {
		swap(&arr[0], &arr[i]);
		printf("%d\n", arr[i]);
		--heap_size;
		AdjustHeap(arr, heap_size, 0);
	}
}

void print_arr(int a[], int len)
{
	int i = 0;
	for (i = 0; i < len; i++)
	{
		printf("%d\n", a[i]);
	}
	printf("\n");
}

int main()
{
	int a[] = {0, 16, 4, 10, 14, 7, 9, 3, 2, 8, 1};
	//int a[] = {16, 4, 10, 14, 7, 9, 3, 2, 8, 1};
	int i = 5;
	
	for (i = 5; i >= 0; i--)
	{
		AdjustHeap(a, 11, i);
	}
	heap_sort(a, 11);
	//print_arr(a, 11);
	return 0;
}

2. 快排

#include <iostream>
using namespace std;

void swap(int &a, int &b) {
	int temp = a;
	a = b;
	b = temp;
}

int partition(int arr[], int p, int r) {
	int x = arr[r];
	int i = p - 1;
	for (int j = p; j <= r - 1; ++j) {
		if (arr[j] <= x) {
			i = i +1;
			swap(arr[i], arr[j]);
		}
	}
	swap(arr[i+1], arr[r]);
	return i + 1;
}


void quickSort(int arr[], int p, int r) {
	if (p < r) {
		int q = partition(arr, p, r);
		quickSort(arr, p, q - 1);
		quickSort(arr, q + 1, r);
	}
}

int main(int argc,char *argv[])
{
	int arr[] = {3, 7, 2, 1, 4, 9};
	quickSort(arr, 0, 5);
	for (int i = 0; i < 6; ++i)
	{
		cout << arr[i] << endl;
	}
	return 0;
}