常用排序算法集合-C实现

之前熟悉C的时候写着玩的，就当做笔记用吧：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define MAX 8

void print_r(int *arr,int len);

static void usage(void)
{
    printf("-s            selection sort
"
           "-b            show unsorted status
"
           "-m            merge sort
"
           "-i            insertion sort
"
           "-I            Information
"
           "-h            help and exit
");
    return;
}

static void usage_info(void)
{
    printf("这是一个排序算法的测试程序
"
           "目前包括选择排序，插入排序和合并排序
");
    return;
}

int* create_arr(int *arr)
{
    srand(time(NULL));
    int i;
    for(i=0;i<MAX;i++)
    {
        arr[i]=rand()%100;
    }
    return arr;
}

void insertion_sort(int arr[])
{

    int temp = 0,j = 0,i = 0;

    for(j = 1;j<MAX;j++)
    {
        i = j-1;
        temp = arr[j];

        while(i >= 0 && arr[i] < temp)
        {
            arr[i+1] = arr[i];
            i--;
        }
        arr[i+1] = temp;
    }
}

void selection_sort(int arr[],int len)
{
    int i,j=0,index,key;

    for(i=0;i < len;i++)
    {
        key = arr[i];
        index = i;
        j = i+1;

        while(j < len)
        {
            if(arr[j] < key)
            {
                key = arr[j];
                index = j;
            }
            j++;
        }

        arr[index] = arr[i];
        arr[i] = key;
    }
    
}
/**
 * start 数组开始下标
 * mid   数组分割下标
 * end   数组结束下标
 */
void merge(int arr[],int start,int mid,int end)
{
    int szie_L,szie_R,i,j,k;
    szie_L = mid+1-start; //左数组大小
    szie_R = end-mid;     //右数组大小
    int arr_L[szie_L],arr_R[szie_R];
    for(i = 0;i < szie_L;i++)
    {
        arr_L[i] = arr[start+i];
    }
    for(j = 0;j < szie_R;j++)
    {
        arr_R[j] = arr[mid+j+1];
    }

    i = 0;
    j = 0;

    for(k = start;k <= end;k++)
    {
        if((i < szie_L) && (j < szie_R))
        {
            if(arr_L[i] <= arr_R[j])
            {
                arr[k] = arr_L[i];
                i++;
            }
            else if(arr_L[i] > arr_R[j])
            {
                arr[k] = arr_R[j];
                j++;
            }
         }
        else if(j >= szie_R)
        {
            arr[k] = arr_L[i];
            i++;
        }
        else
        {
            arr[k] = arr_R[j];
            j++;
        }
    }
}
/**
 * start 数组开始下标
 * end 数组结束下标
 */
void merge_sort(int arr[],int start,int end)
{
    int mid; //用来分割数组的下标
    if(start < end)
    {
        mid = (int)((start+end)/2);
        merge_sort(arr,start,mid);
        merge_sort(arr,mid+1,end);
        merge(arr,start,mid,end);
    }
}

void print_r(int *arr,int len)
{
    int i;
    for(i=0;i<len;i++)
    {
        printf("[%d]=>%d
",i,arr[i]);
    }
}
void main(int argc ,char **argv)
{
    int i,c,sorted=0;
    int arr[MAX];
    create_arr(arr);
    if(argc>1)
    {
        while(-1 != (c = getopt(argc,argv,"hsimIb")))
        {
            switch(c)
            {
                case 'b':
                          printf("before sorting : 
");
                          print_r(arr,MAX);
                          printf("=========================================
");
                          break;
                case 'h':
                          usage();
                          break;
                case 's':
                          selection_sort(arr,MAX);
                          printf("selection sorting : 
");
                          sorted = 1;
                          break;
                case 'i':
                          insertion_sort(arr);
                          printf("insertion sorting : 
");
                          sorted = 1;
                          break;
                case 'm':
                          merge_sort(arr,0,MAX-1);
                          printf("merge sorting : 
");
                          sorted = 1;
                          break;
                case 'I':
                          usage_info();
                          break;
                default : usage();
                          break;
            }
        }

        if(sorted)
        {
            print_r(arr,MAX);
        }
    }
    else
    {
        usage();
        exit(0);
    }
}