排序方法总结和实现

由于很多大神已经总结过各种排序算法的性能及适合坏境，这里便不再总结，只是强调几个重点。

（1）快排的空间复杂度不是o(1)，是o(logn)~o(n)；

（2）四种不稳定的排序算法：简单选择，快排，希尔和堆排序

（3）冒泡排序最有情况下时间复杂度可优化为o(n)；

（4）归并排序的空间复杂度为o(n)；

（5）快排在整体倒序的情况下时间复杂度为o(n2)

（6）建一个最大堆的复杂度为o(n)：具体证明可参考算法导论相关章节

（7）本文代码的归并排序的范围是[   )

（8）本文代码的堆排序为了方便从a[1]开始

（9）在添加了语句using namespace std;语句之后，swap函数才可以使用

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<iostream>
using namespace std;

void print(int *number, int length)
{
    if(number == NULL || length < 1)
        return;

    for(int i = 0; i < length; ++i)
    {
        printf("%d ", number[i]);
    }

    printf("\n");
}

void SelectSort(int number[], int length)
{
    if(number == NULL || length < 1)
        return;

    for(int i = 0; i < length - 1; ++i)
    {
        int k = i;
        for(int j = i + 1; j < length; ++j)
        {
            if(number[k] > number[j])//注意大小于号
                k = j;
        }
        if(k != i)
        {
            swap(number[k], number[i]);
        }
    }
}

void BubbleSort(int number[], int length)
{
    if(number == NULL || length < 1)
        return;

    for(int i = 1; i < length; ++i)
    {
        for(int j = 0; j < length - i; ++j)
            if(number[j] > number[j + 1])
                swap(number[j], number[j + 1]);
    }
}

void InsertSort(int *number, int length)
{
    if(number == NULL || length < 1)
        return;

    for(int i = 1; i < length; ++i)
    {
        int tmp = number[i];
        int j;                   //在外面定义
        for(j = i - 1; j >= 0; j--)
        {
            if(number[j] > number[i])//比较的顺序别弄错了
                number[j + 1] = number[j];//最好检查一下
            else
                break;
        }

        number[j+1] = tmp;
    }
}

void ShellSort(int number[], int length)
{
    if(number == NULL || length < 1)
        return;

    int i, j, d;
    d = length/2;

    while(d >= 1)
    {
        for(i = d; i < length; ++i)
        {
            int tmp = number[i];
            for(j = i - d; j >= 0; j -= d)
            {
                if(number[j] > number[i])
                    number[j + d] = number[j];
                else
                    break;
            }
            number[j + d] = tmp;
        }
        d /= 2;
    }
}

int partion(int number[], int length, int start, int end)
{
    if(number == NULL || length < 1 || start < 0 || end >= length)
        return -1;

    int small = start - 1;
    for(int index = start; index < end; ++index)
    {
        ++small;
        if(number[index] < number[end])
        {
            if(small != index)
                swap(number[small], number[index]);
        }
    }
    ++small;
    swap(number[small], number[end]);

    return small;
}
void QuickSort(int number[], int length, int start, int end)// [start, end]
{
    if(number == NULL || length < 1)
        return;

    if(start == end)
        return;

    int index = partion(number, length, start, end);
    if(index > start)
        QuickSort(number, length, start, index - 1);
    if(index < end)
        QuickSort(number, length, index + 1, end);
}

void MergeSort(int number[], int length, int start, int end, int tmp[])//[start, end)
{
    if(number == NULL || length < 1 || start < 0 || end < 1)
        return;

    //int middle = start + (end - start)/2;
    if(end - start > 1)//while(start < end)
    {
       int middle = start + (end - start)/2;
       int p = start;
       int q = middle;
       int i = start;
       MergeSort(number, length, start, middle, tmp);
       MergeSort(number, length, middle, end, tmp);

       while(p < middle || q < end)
       {
           if(q >= end || (p < middle && number[p] < number[q]))// q < end
                tmp[i++] = number[p++];
           else
               tmp[i++] = number[q++];
       }

       for(int index = start; index < end; ++index)
           number[index] = tmp[index];
    }
}

void AjustHeap(int number1[], int i, int size)
{
    if(number1 == NULL || i < 1 || size < 1)
        return;

    int leftChild = 2 * i;
    int rightChild = 2 * i + 1;
    int max = i;

    if(i <= size/2 )// max <= size 是错的
    {
        if(leftChild <= size && number1[leftChild] > number1[max])
            max = leftChild;
        if(rightChild <= size && number1[rightChild] > number1[max])
            max = rightChild;
        if(max != i)
        {
            swap(number1[max], number1[i]);
            AjustHeap(number1, max, size);
        }

    }

}
void BuildMaxHeap(int number1[], int size)
{
    if(number1 == NULL || size < 1)
        return;

    for(int i = size/2; i >= 1; --i)
        AjustHeap(number1, i, size);
}
void HeapSort(int number1[], int size)
{
    if(number1 == NULL || size < 1)
        return;

    BuildMaxHeap(number1, size);

    for(int i = size; i >= 1; --i)
    {
        swap(number1[1], number1[i]);
        AjustHeap(number1, 1, i - 1);
    }
}
int main()
{
    int number[10] = {3, 5, 2, 10, 4, 1, 8, 7, 6, 9};
    //简单选择排序
    SelectSort(number, 10);
    print(number, 11);
    //冒泡排序
    BubbleSort(number, 10);
    print(number, 10);
    //插入排序
    InsertSort(number, 10);
    print(number, 10);
    //希尔排序
    ShellSort(number, 10);
    print(number, 10);
    //快速排序
    QuickSort(number, 10, 0, 9);
    print(number, 10);

    //归并排序
    int tmp[10];
    MergeSort(number, 10, 0, 10, tmp);
    print(number, 10);
    //堆排序，为了方便，堆排序从a[1]开始
    int number1[11] = {0, 3, 5, 2, 10, 4, 1, 8, 7, 6, 9};
    HeapSort(number1, 10);
    print(number1, 10);
    printf("%d\n",number1[10]);
    return 0;
}

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