算法——排序专题

快速排序(算法导论版)

version1:左边第一个元素为主元

#include<iostream>#include<ctime>#include<stdlib.h>using namespace std;int Partition(int A[], int left, int right)//{int x = A[left];//主元int i = left;for (int j = left+1; j <=right; j++){if (A[j] < x){i++;//if(left!=i)swap(A[i], A[j]);}}swap(A[i], A[left]); return i;}void swap(int &x1, int &x2){int temp;temp = x2;x2 = x1;x1 = temp;}void QuickSort(int A[], int left, int right){if (left < right){int q = Partition(A, left, right);QuickSort(A, left, q - 1);QuickSort(A, q + 1, right);}}int main(){srand((unsigned)time(NULL));int A[999];for (int i = 0; i < 99; i++)A[i] = rand();QuickSort(A, 0, 99);for (int i = 1; i != 99; i++)cout << A[i] << "  ";system("pause");return 0;}

version2:右边最后一个元素为主元

#include<iostream>#include<ctime>#include<stdlib.h>using namespace std;int Partition(int A[],int left,int right)//{int x = A[right];int i = left - 1;for (int j = left; j <= right - 1; j++){if (A[j] <= x){i++;swap(A[i], A[j]);}}swap(A[i + 1], A[right]); //这个版本的swap的是<em>i+1 而不是左边版本的i（因为右边为主元的版本 i+1才是比主元大的“第一个数字”，应该把它换到右边）</em>return i + 1; //同上}void swap(int &x1, int &x2){int temp;temp = x2;x2 = x1;x1 = temp;}void QuickSort(int A[], int left, int right){if (left < right){int q = Partition(A, left, right);QuickSort(A, left, q - 1);QuickSort(A, q+1, right);}}int main(){srand((unsigned)time(NULL));int A[999];for (int i = 0; i < 99; i++)A[i] = rand();QuickSort(A, 0, 99);for (int i = 1; i !=99; i++)cout << A[i] << "  ";system("pause");return 0;}

2.BIS

#include<iostream> //折半插入排序#include<ctime>using namespace std;void BIS(int A[], const int left, const int right)//在lefr到i-1的地方 查找i要插入的位置.{int temp;int low, high, middle;int i;for ( i = left + 1; i <=right; i++){temp = A[i]; low = left; high = i - 1;while (low <= high){  //与直接插入相比，不再是一个一个地比较，引入了二分搜索.middle = (low + high) / 2;if (temp < A[middle])high = middle - 1;else low = middle + 1;}for (int k = i - 1; k >= low; k--){A[k + 1] = A[k];}A[low] = temp;}}/*int main(){srand((unsigned)time(NULL));int B[10000];for (int i = 0; i != 10000; i++)B[i] = rand();BIS(B,0,9999);for (int i = 0; i != 100; i++)cout << B[i] << " ";system("pause");return 0;}*/

3.冒泡排序

#include<iostream>//冒泡排序#include<ctime>using namespace std;void Bubble(int A[], int n){bool exchange;for (int i = 1; i < n; i++){exchange = false;for (int j = 1; j <= n - i; j++){if (A[j - 1]>A[j])swap(A[j - 1], A[j]);exchange = true;}if (exchange == false)return;}}/*int main(){srand((unsigned)time(NULL));int B[10000];for (int i = 0; i != 10000; i++)B[i] = rand();Bubble(B, 10000);for (int i = 0; i != 10000; i++)cout << B[i] << " ";system("pause");return 0;}*/

4.直接插入

#include<iostream> //插入排序#include<ctime>using namespace std;void InsertSort(int A[], const int left, const int right){int temp; int j;for (int i = left + 1; i <= right; i++){if (A[i-1] > A[i]){temp = A[i]; j = i - 1;do{A[j + 1] = A[j]; j--;} while (j >= left && temp < A[j]);A[j + 1] = temp;}}}void InsertSort_1(int A[], const int left, const int right){int temp;for (int i = left + 1; i <= right; i++){if (A[i] < A[i - 1]){temp = A[i]; int back = i - 1;//j做为要后退的数组标号.do{A[back + 1] = A[back]; back--;} while (back >= left && temp < A[back]);A[back + 1] = temp;}}}/*int main(){srand((unsigned)time(NULL));int B[10000];for (int i = 0; i != 10000; i++)B[i] = rand();InsertSort_1(B, 0,9999);for (int i = 0; i != 100; i++)cout << B[i] << " "; system("pause");return 0;}*/  

5.归并排序

#include<iostream>using namespace std;//将有二个有序数列a[first...mid]和a[mid...last]合并。void mergearray(int a[], int first, int mid, int last, int temp[]){int i = first, j = mid + 1;int m = mid, n = last;int k = 0;while (i <= m && j <= n){if (a[i] <= a[j])temp[k++] = a[i++];elsetemp[k++] = a[j++];}while (i <= m)temp[k++] = a[i++];while (j <= n)temp[k++] = a[j++];for (i = 0; i < k; i++)a[first + i] = temp[i];}void mergesort(int a[], int first, int last, int temp[]){if (first < last){int mid = (first + last) / 2;mergesort(a, first, mid, temp);    //左边有序mergesort(a, mid + 1, last, temp); //右边有序mergearray(a, first, mid, last, temp); //再将二个有序数列合并}}/*bool MergeSort(int a[], int n){int *p = new int[n];if (p == NULL)return false;mergesort(a, 0, n - 1, p);delete[] p;return true;}*//*int main(){int A[] = { 3, 4, 5, 6, 1, 2, 10, 9, 8, 7 };int B[10];mergesort(A, 0, 9, B);for (int i = 0; i != 10; i++)cout << B[i] << " ";return 0;}*/

6.希尔排序

#include<iostream>#include<ctime>using namespace std;void ShellSort(int A[],int left,int right){int gap = left + right - 1;int temp; do{gap = gap / 3 + 1;for (int i = left+gap; i <= right; i++){temp = A[i]; int j = i - gap;if (temp < A[i - 1])do{A[j + gap] = A[j]; j = j - gap;} while (j >= left &&temp < A[j]);A[j + gap] = temp;}} while (gap>1);}/*int main(){srand((unsigned)time(NULL));int B[10000];for (int i = 0; i != 10000; i++)B[i] = rand();ShellSort(B, 0, 9999);for (int i = 0; i != 100; i++)cout << B[i] << " ";system("pause");return 0;}*/