常用排序

 本博客参考常用排序算法总结（一）

#include <iostream>
using namespace std;

void chooseSort(int ff[],int n){
    for(int i=0;i<n;i++){
        int min = i;//index of min number
        //find min index--------time
        for(int j=i+1;j<n;j++){
            if(ff[min]>ff[j]){
                min = j;
            }
        }
        //exchange ff[i] and ff[min]-----memory and time
        int temp = ff[i];
        ff[i] = ff[min];
        ff[min] = temp;
    }
}

void insertSort(int ff[],int n){
    for (int i = 1; i < n; i++) {
        for (int j = i; j > 0; j--) {
            if(ff[j]<ff[j-1]){
                int temp = ff[j];
                ff[j] = ff[j-1];
                ff[j-1] = temp;
            }
        }
    }
}

void insertDichotomySort(int ff[],int n){
    for(int i=1;i<n;i++){
        int get = ff[i];//sorted number
        int left = 0;
        int right = i-1;
        while (left <= right) {
            int middle = (left+right)/2;
            if(get<ff[middle]){
                right = middle-1;
            }else{
                left = middle+1;
            }
        }
        for(int j=i-1;j>=left;j--){
            ff[j+1] = ff[j];
        }
        ff[left] = get;
    }
}

void shellSort(int ff[], int n){
    int h=0;
    while(h<=n){
        h=3*h+1;//increment
    }
    while(h>=1){
        for(int i=h;i<n;i++){//insert sort
            int get = ff[i];
            int j= i-h;
            while(j>=0&&get<ff[j]){
                ff[j+h] = ff[j];
                j=j-h;
            }
            ff[j+h] = get;
        }
        h = (h-1)/3;//decline
    }
}

void Merge(int ff[],int left,int mid,int right){
    int len = right-left+1;
    int *temp = new int[len];// 辅助空间O(n)
    int index = 0;
    int i = left;// 前一组数的起始元素
    int j = mid+1;// 后一组数的起始元素
    while(i<=mid&&j<=right){
        temp[index++] = ff[i]<=ff[j]?ff[i++]:ff[j++];//=保证归并排序的稳定性
    }
    //把末尾数加上
    while (i <= mid) {
        temp[index++] = ff[i++];
    }
    while (j <= right) {
        temp[index++] = ff[j++];
    }
    //把排序后的temp赋值回原数组
    for (int k = 0; k < len; k++) {
        ff[left++] = temp[k];
    }
}
//归并排序的递归实现，自顶向下
void mergeSortRecursion(int ff[],int left,int right){
    if (left == right) {
        return;
    }
    int mid = (left+right)/2;
    mergeSortRecursion(ff,left,mid);
    mergeSortRecursion(ff, mid + 1, right);
    Merge(ff, left, mid, right);
}
//归并排序的非递归实现，自下向顶
void mergeSortIteration(int ff[],int len){
    int left,mid,right;
    for (int i = 1; i < len; i *= 2) {
        left = 0;
        while (left + i < len) {
            mid = left+i-1;
            right = mid+i<len?mid+i:len-1;
            Merge(ff, left, mid, right);
            left = right+1;
        }
    }
}

//quick sort
int partition(int ff[],int left,int right){
    int pivot = ff[right];//选择最后一个数作为基准数
    int blank = right;//填坑法
    while(left<right){
        //从左边找到第一个大于pivot的，放到后面的坑里
        while(left<right&&ff[left]<=pivot){
            left++;
        }
        ff[blank] = ff[left];
        blank = left;
        //从右边找到第一个小于pivot的，放到前面的坑里
        while(left<right&&ff[right]>=pivot){
            right--;
        }
        ff[blank] = ff[right];
        blank = right;
    }
    //最后剩的那个坑放pivot
    ff[blank] = pivot;
    return blank;
}
void quickSort(int ff[],int left,int right){
    if(left>=right){
        return;
    }
    int index = partition(ff, left, right);
    quickSort(ff,left,index-1);
    quickSort(ff, index+1, right);
}

int main() {
    int f[100]={3,1,6,5,8,2,0,7,4};
    quickSort(f,0,8);
    for(int i=0;i<9;i++){
        cout<<f[i]<<" ";
    }
    cout<<endl;

}