快速排序和归并排序

#include<iostream>
using namespace std;
#define ElemType int
const int Maxn=105;
int Partition(ElemType A[],int low,int high){
    ElemType pivot=A[low];
    int i=low,j=high;
    while(i<j){
        while(i<j&&A[j]>=pivot)j--;
        A[i]=A[j];
        while(i<j&&A[i]<=pivot)i++;
        A[j]=A[i];
    }
    A[i]=pivot;
    return i;
}
void QuickSort(ElemType A[],int low,int high){
    if(low<high){
        int pivotPos=Partition(A,low,high);
        QuickSort(A,low,pivotPos-1);
        QuickSort(A,pivotPos+1,high);
    }
}
//时间：最好和平均O(n*log2(n))    最坏O(n^2)
//空间：最好和平均O(log2(n))    最坏O(n)
//不稳定 
void Merge(ElemType A[],int low,int mid,int high){
    int i,j,k;
    ElemType *B=new ElemType[Maxn];
    for(k=low;k<=high;k++)B[k]=A[k];
    for(i=low,j=mid+1,k=low;i<=mid&&j<=high;k++){
        if(B[i]<=B[j])
            A[k]=B[i++];
        else
            A[k]=B[j++];
    }
    while(i<=mid)A[k++]=B[i++];
    while(j<=high)A[k++]=B[j++];
    delete[] B;
    
}
void MergeSort(ElemType A[],int low,int high){
    if(low<high){
        int mid=(low+high)/2;
        MergeSort(A,low,mid);
        MergeSort(A,mid+1,high);
        Merge(A,low,mid,high);
    }
}
//时间：O(n*log2(n))
//空间：O(n)
//稳定 
int main(){
    int n;
    cin>>n;
    ElemType arr[Maxn];
    for(int i=0;i<n;i++){
        cin>>arr[i];
    }
    MergeSort(arr,0,n-1);
    for(int i=0;i<n;i++){
        cout<<arr[i]<<" ";
    }
    
    return 0;
}
//12
//8 2 9 3 23 7 2 6 4 1 16 7

 

来源：https://www.cnblogs.com/lyt888/p/12540108.html