C++中的几种排序算法

SortAlgorithm.h

代码如下:

#include <vector>
using namespace std;

class SortAlgorithm
{
public:
    SortAlgorithm(int = 10);
    void displayVector();
    void swap(int &, int &);

void insertSort();                     //O(n^2)
    void selectSort();                    //O(n^2)
    void mergeSort();                    //O(n log n)
    void bubbleSort();                  //O(n^2)
    void quickSort(  int , int  );     //worst: O(n^2),  best: O(n log n)

int partition( int , int  );
    void sortSubVector(int , int );
    void merge(int , int , int , int );
private:
    int size;
    vector< int > source;
    vector< int > temp;

};

SortAlgorithm.cpp

代码如下:

#include <iostream>
#include <cstdlib> // prototypes for functions srand and rand
#include <ctime> // prototype for function time
#include <algorithm> // prototype for sort function
#include "SortAlgorithm.h" // class BinarySearch definition
using namespace std;

SortAlgorithm::SortAlgorithm(int vectorSize)
{
    size = ( vectorSize > 0 ? vectorSize : 10 ); // validate vectorSize
    srand( time( 0 ) ); // seed using current time

// fill vector with random ints in range 10-99
    for ( int i = 0; i < size; i++ )
           source.push_back( 10 + rand() % 90 ); // 10-99

temp = source;
}

void SortAlgorithm::insertSort()
{
    int insert;
    for(int next = 1; next < size; next++){
        insert = temp[next];
        int moveItem = next;

while((moveItem > 0) && (temp[moveItem - 1] > insert)){
            temp[moveItem] = temp[moveItem - 1];
            moveItem--;
        }

temp[moveItem] = insert;
    }
}

void SortAlgorithm::selectSort()
{
    int loop = size - 1;
    int smallest;

for(int i = 0; i < loop; i++){
        smallest = i;

for(int j = i + 1; j < size; j++){
            if(temp[j] < temp[smallest])
                smallest = j;
        }

swap(temp[i], temp[smallest]);
    }
}

void SortAlgorithm::mergeSort()
{
    sortSubVector(0, size - 1);
}

void SortAlgorithm::bubbleSort()
{
       int comp; // used to control for loop and for subscripts
       bool swapCheck = true; // was a swap made?

for ( int pass = 1; pass < size && swapCheck; pass++ ) {
        swapCheck = false; // assume no swaps will be made

// traverse and compare unsorted part of vector
        for ( comp = 0; comp < size - pass; comp++ ){

// compare adjacent vector elements
            if ( temp[ comp ] > temp[ comp + 1 ] ) {
                swap(temp[comp], temp[comp + 1]);
                swapCheck = true;
                 } // end if

} // end inner for
    } // end outer for
}

void SortAlgorithm::quickSort(int first, int last )
{
   int currentLocation;

if ( first >= last )
      return;

currentLocation = partition( first, last ); // place an element
   quickSort( first, currentLocation - 1 ); // sort left side
   quickSort( currentLocation + 1, last ); // sort right side
} // end function quickSortHelper

// partition the vector into multiple sections
int SortAlgorithm::partition( int left, int right )
{
   int position = left;

// loop through the portion of the vector
   while ( true )
   {
   //first: from right ro left
      while ( temp[ position ] <= temp[ right ] && position != right )
         --right;

if ( position == right )
         return position;

if ( temp[ position ] > temp[ right ])
      {
         swap( temp[ position ], temp[ right ] );
         position = right;
      } // end if
   //second: from left to right
      while ( temp[ left ] <= temp[ position ] && left != position )
         ++left;

if ( position == left )
         return position;

if ( temp[ left ] > temp[ position ] )
      {
         swap( temp[ position ], temp[ left ] );
         position = left;
      } // end if
   } // end while
} // end function partition

void SortAlgorithm::sortSubVector(int low, int high)
{
    if((high - low) >= 1){
        int middle1 = (low + high) / 2;
        int middle2 = middle1 + 1;

/*cout << "split:   ";
        displaySubVector(low, high);
        cout << endl << "       ";
        displaySubVector(low, middle1);
        cout << endl << "       ";
        displaySubVector(middle2, high);
        cout << endl << endl;*/

sortSubVector(low, middle1);
        //cout << "Stop here1. low = " << low << ", middle1 = " << middle1 << endl;
        sortSubVector(middle2, high);
        //cout << "Stop here2. middle2 = " << middle2 << ", high = " << high << endl;

merge(low, middle1, middle2, high);

}
}

void SortAlgorithm::merge(int left, int middle1, int middle2, int right)
{
    int leftIndex = left;
    int rightIndex = middle2;
    int combinedIndex = left;
    vector<int> combined(size);

/*cout << "merge:   ";
    displaySubVector(left, middle1);
    cout << endl << "       ";
    displaySubVector(middle2, right);
    cout << endl;*/

while(leftIndex <= middle1 && rightIndex <= right){
        if(temp[leftIndex] <= temp[rightIndex])
            combined[combinedIndex++] = temp[leftIndex++];
        else
            combined[combinedIndex++] = temp[rightIndex++];
    }

if(leftIndex == middle2){
        while(rightIndex <= right)
            combined[combinedIndex++] = temp[rightIndex++];
    }
    else{
        while(leftIndex <= middle1)
            combined[combinedIndex++] = temp[leftIndex++];
    }

for(int i = left; i <= right; i++)
        temp[i] = combined[i];

/*cout << "       ";
    displaySubVector(left, right);
    cout << endl << endl;*/
}

void SortAlgorithm::swap(int &x, int &y)
{
    int t;

t = x;
    x = y;
    y = t;
}

void SortAlgorithm::displayVector()
{
    for(int i = 0; i < size; i++){
        cout << " " << temp[i];
        if((i + 1) % 10 == 0)
            cout << endl;
    }

cout << endl;

temp = source;
}

main.cpp

代码如下:

#include <iostream>
#include "SortAlgorithm.h" // class BinarySearch definition
#include "BucketSort.h"
using namespace std;

int main()
{
    int num;
    cout << "Please input the integer number you want to sort:  ";
    cin >> num;

SortAlgorithm sortVector(num);
    cout << "Unsort elements: \n";
    sortVector.displayVector();

sortVector.insertSort();
    cout << "\nInsert sorted elements: \n";
    sortVector.displayVector();

sortVector.selectSort();
    cout << "\nSelect sorted elements: \n";
    sortVector.displayVector();

sortVector.mergeSort();
    cout << "\nMerge sorted elements: \n";
    sortVector.displayVector();

sortVector.bubbleSort();
    cout << "\nBubble sorted elements: \n";
    sortVector.displayVector();

sortVector.quickSort(0, num - 1);
    cout << "\nQuick sorted elements: \n";
    sortVector.displayVector();

/*BucketSort bucketSortVector( num ); // create BucketSort object

cout << "Vector elements in original order:\n";
   bucketSortVector.displayElements();

bucketSortVector.sort(); // sort the vector

cout << "\nVector elements in sorted order:\n";
   bucketSortVector.displayElements();*/
}