算法5--排序

主要是一些常见的排序方法的实现

1 冒泡排序算法

 

排序算法的理论和实现比较简单；

 

对于冒泡排序算法的改进，一种比较好的方法是，每次中间排序之后，都进行排序状态检测，如果已经排好序，就退出排序过程，否则基于冒泡排序；

 

但是：对于数组排序状态的检测，我没有比较好的办法；如果个数比较少，还可以容易得出，但是数组元素个数比较多的时候，该如何做？

 

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

int sortjudge(int *a,int len)
{
    if (/* condition */)
    {
        /* code */
    }
}
void bubblesort(int *a,int len)
{
    int temp;
    for (int i = 0; i < len-1; i++)
    {
        for (int j = len-1; j>i; j--)
        {
            if (a[j-1]>a[j])
            {
                temp=a[j-1];
                a[j-1]=a[j];
                a[j]=temp;
            }
        }
        printf("the %d down sort answer :", i+1);
        for (int k = 0; k < len; k++)
        {
            printf("%d ", a[k]);
        }
        printf("
");
    }

}


int main()
{
    int array[SIZE];
    srand(time(NULL));
    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");
    bubblesort(array,SIZE);
    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

2 选择排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

void selectionsort(int *a , int len)
{
    int temp;
    for (int i=0; i<len-1; i++)
    {
        int k=i;
        for (int j=i+1; j<len; j++)
        {
            if (a[j]<a[k])
            {
                k=j;
            }
        }
        if (k!=i)
        {
            temp=a[i];
            a[i]=a[k];
            a[k]=temp;
        }
        printf("the %d sorted answer is :" , i+1);
        for (int m = 0; m<len; m++)
        {
            printf("%d",a[m]);
        }
        printf("
");
    }
}


int main()
{
    int array[SIZE];
    srand(time(NULL));
    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");
    selectionsort(array,SIZE);
    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

3  插入排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

void insertionsort(int *a,int len)
{
    for (int i = 1; i < len; i++)
    {
        int t=a[i];
        int j=i-1;
        while(j>=0&&t<a[j])
        {
            a[j+1]=a[j];
            j--;
        }
        a[j+1]=t;
        printf("the %d step sort answer:", i);
        for (int k = 0; k < len; k++)
        {
            printf("%d ",a[k] );
        }
        printf("
");
    }
}

int main()
{
    int array[SIZE];

    srand(time(NULL));

    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000+100;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");
    insertionsort(array,SIZE);
    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

4 shell排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

void shellsort(int *a,int len)
{
    int times=0;
    for (int i = len/2; i >=1; i/=2)
    {
        for (int j = i; j < len; j++)
        {
            int temp=a[j];
            int k=j-i;
            while(k>=0&&temp<a[k])
            {
                a[k+i]=a[k];
                k-=i;
            }
            a[k+i]=temp;
        }
        times=times+1;
        printf("the %d steps answer:", times);
        for (int h = 0; h < len; h++)
        {
            printf("%d ",a[h]);
        }
        printf("
");
    }
}
int main()
{
    int array[SIZE];
    srand(time(NULL));
    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000+100;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");
    shellsort(array,SIZE);
    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

5 快速排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

void exchange(int m,int n)
{
    int temp=0;
    temp=m;
    m=n;
    n=temp;
}

int partion(int *a,int left,int right)
{
    int x=a[right];
    int i=left;
    for (int j=left ; j <= right; j++)
    {
        if (a[j]<=x)
        {
            i=i+1;
            exchange(a[i],a[j]);
        }
    }
    exchange(a[i+1],a[right]);
    printf("the partion postion is 
", i);
    return i;
}


void quicksort(int *a,int left,int right)
{
    if (left<right)
    {
        int q=partion(a,left,right);
        quicksort(a,left,q-1);
        quicksort(a,q+1,right);
    }
}

int main()
{
    int array[SIZE];

    srand(time(NULL));

    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000+100;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");

    quicksort(array,0,SIZE-1);

    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

6 堆排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10

int left(int i){return i*2;}

int right(int i){return i*2+1;}

int parent(int i){return i/2;}

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

void max_heapify(int *a,int i)
{
    int length=SIZE;
    int l=left(i);
    int r=right(i);
    int largest;
    if (l<=SIZE&&a[l]>a[i])
    {
        largest=l;
    }
    else
        largest=i;
    if (r<=length&&a[r]>a[i])
    {
        largest=r;
    }
    if (largest!=i)
    {
        swap(a[largest],a[i]);
        max_heapify(a,largest);
    }
}

void build_max_heap(int *a)
{
    int length=SIZE;
    for (int i = length/2; i >0; i--)
    {
        max_heapify(a,i);
    }
}


void heapsort(int *a)
{
    int length=SIZE;
    build_max_heap(a);

    for (int i = length; i >=2; i--)
    {
        printf("%d ", a[0]);
        swap(a[0],a[i]);
        length=length-1;
        max_heapify(a,1);
    }
}


int main()
{
    int array[SIZE];
    int length=10;
    srand(time(NULL));

    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000+100;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");

    heapsort(array);

    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}

 7 归并排序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define SIZE 10
#define big NULL
/*
void merge(int *a,int p,int q,int r)
{
    int len1=q-p+1;
    int len2=r-q+1;
    int len3=len1+1;
    int len4=len2+1;
    int l[len3]={};
    int r[len4]={};
    for (int i = 0; i < len1; i++)
    {
        l[i]=a[p+i-1];
    }
    for (int j = 0; j < len2; j++)
    {
        r[j]=a[q+j];
    }
    int l[len3]=big;
    int r[len4]=big;
    int i=1;
    int j=1;
    for (int k = p; k < r; k++)
    {
        if (l[i]<=r[j]&&l[i]!=big&&r[j]!=big)
        {
            a[k]=l[i];
            i++;
        }
        else
        {
            a[k]=r[j];
            j++;
        }
    }
}
*/
void merge2(int *a,int p,int q,int r)
{
    int len1=q-p+1;
    int len2=r-q+1;
    int len3=r-p+1;
    int left[len1];
    int right[len2];
    for (int i = 0; i < len1; i++)
    {
        left[i]=a[p+i-1];
    }
    for (int j = 0; j < len2; j++)
    {
        right[j]=a[q+j];
    }
    while(len1>=0&&len2>=0)
    {
        a[len3--]=left[len1]>=right[len2] ? left[len1] : right[len2];
    }
    while(len1>0)
    {
        a[len3--]=left[len1--];
    }
    while(len2>0)
    {
        a[len3--]=right[len2--];
    }

}


void mergesort(int *a,int p,int r)
{
    if (p<r)
    {
        int q=(p+r)/2;
        mergesort(a,p,q);
        mergesort(a,q+1,r);
        merge2(a,p,q,r);
    }
}

int main()
{
    int array[SIZE];

    srand(time(NULL));

    for (int i = 0; i < SIZE; i++)
    {
        array[i]=rand()/1000+100;
    }
    printf("before sort:
");
    for (int j = 0; j < SIZE; j++)
    {
        printf("%d ",array[j]);
    }
    printf("
");

    mergesort(array,0,SIZE-1);

    printf("after sort:
");
    for (int k = 0; k < SIZE; k++)
    {
        printf("%d ",array[k]);
    }
    printf("
");
    return 0;
}