【排序】冒泡排序+快速排序

冒泡排序：

//复杂度：O(n^2)
//比较次数：n*(n-1)/2 ；移动等数量级
#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
const int INF = 0x7fffffff;
void Bubble_sort(int* A, int n)
{
    for(int i = n-1; i >= 0; i--)
    {
        A[n] = A[i];
        int _max = -INF, pos = -1;
        for(int j = 0; j <= i; j++)
        {
            if(_max < A[j]) _max = A[j], pos = j;
        }
        A[pos] = A[n];
        A[i] = _max;
    }
    for(int i = 0; i < n; i++)  {if(i) printf(" "); printf("%d", A[i]);}
    printf("\n");
}

int main()
{
    int A[10] = {1, 9, 3, 7, 5, 2, 8, 4, 6, 10};
    Bubble_sort(A, 10);
    return 0;
}

 

快速排序：

//一趟排序将待排记录分割成独立的两部分，其中一部分记录的关键字均比另一部分记录的关键字小，
//则可分别对这两部分记录继续进行排序，以达到整个序列有序
//复杂度：O(nlnn)
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<list>
using namespace std;
//改进前
//void Exchange(int* L, int i, int j)
//{
//    int tmp = L[i]; L[i] = L[j]; L[j] = tmp;
//}

int Partition(int* L, int low, int high){
    L[0] = L[low];
    int pivotkey = L[low];
    while(low < high)
    {
        while(low < high && L[high] >= pivotkey) high--;
        //Exchange(L, low, high);
        L[low] = L[high];
        while(low < high && L[low] <= pivotkey) low++;
        //Exchange(L, low, high);
        L[high] = L[low];
    }
    L[low] = L[0];
    return low;//返回枢轴所在位置
}
void Quick_sort(int* L, int low, int high)
{
    if(low >= high)  return ;
    int pivotkey = Partition(L, low, high);
    Quick_sort(L, low, pivotkey-1);
    Quick_sort(L, pivotkey+1, high);
}

int main()
{
    int L[11] = {0, 3, 9, 1, 7, 5, 2, 8, 4, 6, 10};
    Quick_sort(L, 1, 10);
    for(int i = 1; i <= 10; i++) {if(i) printf(" "); printf("%d", L[i]);}
    printf("\n");
    return 0;
}