整理几个简单排序（选择，插入，冒泡）

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 20

static void show(int *arr, int len)
{
    int index;
    for(index = 0; index < len; index++)
    {
        printf("%d ", arr[index]);
    }
    printf("\n");
}

static void swap(int *left, int *right)
{
    int tmp = *left;
    *left = *right;
    *right = tmp;
}

/**
 * 选择排序思想：依次将未排序的数组中的最小数放入pos所在位置，pos从0至N-1
 * -->前N-1个数放好位置，最后一个数就不用管了
 */
static void select_sort(int *arr, int len)
{
    int pos,index;
    int min_index;
    for(pos = 0; pos < len - 1; pos++)
    {
        min_index = pos;
        for(index = pos + 1; index < len; index++)
        {
            if(arr[index] < arr[min_index])
                min_index = index;
        }
        if(min_index != pos)
        {
            swap(arr + pos, arr + min_index);
        }
    }
}

static void insert_sort(int *arr, int len)
{
    int pos,index;
    int key;
    for(pos = 1; pos < len; pos++)
    {
        key = arr[pos];
        for(index = pos - 1; index >= 0; index--)
        {
            if(key < arr[index])
            {
                arr[index+1] = arr[index];
            }else
            {
                break;
            }
        }
        arr[index+1] = key;
    }
}

static void bubble_sort(int *arr, int len)
{
    int pos,index;
    for(pos = 0; pos < len - 1; pos++)
    {
        for(index = 0; index < len - 1 - pos; index++)
        {
            if(arr[index] > arr[index + 1])
            {
                swap(arr + index, arr + index + 1);
            }
        }
    }
}

static void bubble_sort2(int *arr, int len)
{
    int left, right, index;
    left = 0;
    right = len - 1;

    while(left < right)
    {
        for(index = left; index < right; index++)
        {
            if(arr[index] > arr[index+1])
            {
                swap(arr+index, arr+index+1);
            }
        }
        right--;
        if(left == right)
        {
            break;
        }
        for(index = right; index > left; index--)
        {
            if(arr[index] < arr[index-1])
            {
                swap(arr + index, arr + index -1);
            }
        }
        left++;
    }
}

int main(int argc, char *argv[])
{
    int arr[N], index;
    srand(time(NULL));
    for(index = 0; index < N; index++)
    {
        arr[index] = rand()%100 + 1;
    }
    show(arr, N);
    bubble_sort2(arr, N);
    show(arr, N);
    system("pause");
    return 0;
}

整理几个简单排序，用于时常复习。