C语言排序

排序算法

快速排序

C语言快速排序qsort(数组，长度，元素大小，cmp函数(*,*))//注意函数cmp的参数为指针

#include <stdio.h>
#include <stdlib.h>
#include <stdlib.h>   //qsort函数
int cmp (int a,int b)
{
    return a -b;
}
 
//0 3 2 1 4 5 6 9 8 7
int main()
{
    inta[10],i,x;
    for(i=0;i<10; i++)
    {
       scanf("%d",&a[i]);
    }
   qsort(a,10,sizeof(a[0]),cmp);
    for(i=0;i<10; i++)
    {
      printf("%d ",a[i]);
    }
    return 0;
}
自定义qsort
 
void qsort2(int a[],int l,int r){
    if(l<r){
        inti=l,j=r;
        intk=a[i];
       while(i<j){
           while(i<j&&a[j]>=k){
               j--;
            }
            a[i]=a[j];
           while(i<j&&a[i]<=k){
               i++;
            }
           a[j]=a[i];
        }
        a[i]=k;
       qsort2(a,l,i-1);
       qsort2(a,i+1,r);
    }
}

冒泡排序

void bubble(int a[],int n)
{
    int i,j;
    for(i=0;i<n-1; i++)
    {
       for(j=n-1; j>i; j--)
        {
           if(a[j]<a[j-1])
            {
               int t=a[j];
               a[j]=a[j-1];
               a[j-1]=t;
            }
        }
    }
}

归并排序

void merge(int a[],int l,int m,int r){
    inttemp[r-l+1];
    inti=l,j=m+1,k=0;
   while(i<=m&&j<=r){
       if(a[i]<a[j])temp[k++]=a[i++];
        elsetemp[k++]=a[j++];
    }
   while(i<=m){
       temp[k++]=a[i++];
    }
   while(j<=r){
       temp[k++]=a[j++];
    }
   for(i=0;i<k;i++){
       a[l+i]=temp[i];
    }
}
 
void mergeSort(int a[],int l,int r){
    if(l<r){
        intm=(l+r)/2;
       mergeSort(a,l,m);
       mergeSort(a,m+1,r);
       merge(a,l,m,r);
    }
}

选择排序

void selectSort(int a[],int n){
    int i,j;
   for(i=0;i<n;i++){
        intk=i;
       for(j=i+1;j<n;j++){
           if(a[j]>a[k]){
               k=j;
            }
           if(k!=i){
               int t=a[i];
               a[i]=a[k];
               a[k]=t;
            }
        }
    }
 
}

堆排序

#include <stdio.h>
#include <stdlib.h>
 
typedef struct heap_t{
       int *arr;         //point for an array to store heap value.
       intheapMaxIndex; //heap element max indexnumber
       intarrLength; //array length of arr
 
}Heap;
 
 
void printArr(int *p, int size)
{
       int i;
       for(i=0;i<size;i++)
       {
              printf("%d",p[i]);
       }
}
 
void maxHeapify(Heap *hp, unsigned int nodei)
{
       unsignedint l = (nodei+1) << 1 - 1;  //leftchild = 2i-1, -1 ?:arr[0..n-1]
       unsignedint r = (nodei+1) << 1 ;      //right child = 2i
       unsignedint largest = 0;
       intheapMaxI = hp->heapMaxIndex;
 
       if(l<= heapMaxI && hp->arr[l] > hp->arr[nodei])
              largest= l ;
       else
              largest= nodei ;
 
       if(r<= heapMaxI && hp->arr[r] > hp->arr[largest])
              largest= r ;
 
       if(largest!=nodei)
       {
              //exchange
              inttmp ;
              tmp= hp->arr[largest];
              hp->arr[largest]= hp->arr[nodei];
              hp->arr[nodei]= tmp;
 
              maxHeapify(hp,largest);
       }else{
              return;
       }
 
}
 
 
Heap *createHeap(int *arrp, int arrLength,Heap *heap)
{
 int i;
 heap->arr =arrp;
 heap->heapMaxIndex = arrLength-1;
 heap->arrLength = arrLength;
 
 //for an heapa[0..n-1]; a[(n/2)..n-1] all are leaves
 for(i =arrLength>>1-1; i >=0; i--)
 maxHeapify(heap,i);
 return heap;
}
 
 
void heapSort(Heap *hp)
{
       int tmp;
       int last;
       while(hp->heapMaxIndex>0)
       {
              last= hp->heapMaxIndex ;
              //exchange
              tmp= hp->arr[last];
              hp->arr[last]= hp->arr[0];
              hp->arr[0]= tmp;
              hp->heapMaxIndex-= 1;
              maxHeapify(hp,0); //make heap from root node 0 to heapMaxIndex
       }
 
}
 
int main()
{
       inta[]={15,25,32,23,1,-4,35,2,-85,42,0,12,26,56,45,12,145,17,25,21};
       printArr(a,20);
       printf("
");
 
       Heaphpa,*phpa;
       phpa=  createHeap(a,20,&hpa);
       heapSort(phpa);
 
       printArr(a,20);
       putchar('
');
       return 0;
}