排序算法（C++实现）

#include <vector>
using std::vector;

template<typename T>
void swap(vector<T> &a, int i, int j)
{
    T tmp = a[i];
    a[i] = a[j];
    a[j] = tmp;
}

//简单插入排序
template<typename T>
void insertionSort(vector<T> &a)
{
    for(int p=1; p!=a.size(); ++p)
    {
        int tmp = a[p], j;
        for(j = p; j>0&&a[j-1]>tmp; --j)
            a[j] = a[j-1];
        a[j] = tmp;
    }
}

//堆排序
//把将要进行排序的元素依次入堆，再逐个弹出，便得到排好序的元素序列。
//堆的C++实现：http://www.cnblogs.com/pczhou/p/4648146.html

//归并排序
template<typename T>
void mergeSort(vector<T> &a)
{
    vector<T> tmpA(a.size());
    mergeSort(a, tmpA, 0, a.size()-1);
}
template<typename T>
void mergeSort(vector<T> &a, vector<T> &tmpA, int left, int right)
{
    if(left<right)
    {
        int mid = (left+right)/2;
        mergeSort(a, tmpA, left, mid);
        mergeSort(a, tmpA, mid+1, right);
        merge(a, tmpA, left, mid+1, right);
    }
}
template<typename T>
void merge(vector<T> &a, vector<T> &tmpA, int leftPos, int rightPos, int rightEnd)
{
    int leftEnd = rightPos-1, tmpPos = leftPos;
    int numElements = rightEnd-leftPos+1;

    while(leftPos<=leftEnd&&rightPos<=rightEnd)
    {
        if(a[leftPos]<a[rightPos])
            tmpA[tmpPos++] = a[leftPos++];
        else
            tmpA[tmpPos++] = a[rightPos++];
    }
    while(leftPos<=leftEnd)
        tmpA[tmpPos++] = a[leftPos++];
    while(rightPos<=rightEnd)
        tmpA[tmpPos++] = a[rightPos++];
    for(; numElements; --numElements, --rightEnd)
        a[rightEnd] = tmpA[rightEnd];
}

//快速排序
//（采用三数中值分割法确定枢纽元）
template<typename T>
void quickSort(vector<T> &a)
{
    quickSort(a, 0, a.size()-1);
}
template<typename T>
const T& median3(vector<T> &a, int left, int right)
{
    int mid = (left+right)/2;
    if(a[left]<a[mid]&&a[mid]<a[right]||a[right]<a[mid]&&a[mid]<a[left])
        swap(a, mid, right);
    else if(a[mid]<a[left]&&a[left]<a[right]||a[right]<a[left]&&a[left]<a[mid])
        swap(a, left, right);
    return a[right];
}
template<typename T>
void quickSort(vector<T> &a, int left, int right)
{
    if(left<right)
    {
        T pivot = median3(a, left, right);
        int i=left-1, j=left;
        for(; j<right; ++j)
        {
            if(a[j]<pivot)
            {
                ++i;
                swap(a, i, j);
            }
        }
        swap(a, i+1, right);

        quickSort(a, left, i);
        quickSort(a, i+2, right);
    }
}

//桶排序
//假设：所有输入数据均为非负，且不超过M
const int M = 100;
void bucketSort(vector<int> &a)
{
    vector<int> count(M+1);
    for(int i=0; i!=count.size(); ++i) count[i] = 0;
    for(int i=0; i!=a.size(); ++i) ++count[a[i]];
    int k = 0;
    for(int i=0; i!=count.size(); ++i)
        for(int j=0; j<count[i]; ++j)   a[k++] = i;
}

测试代码:

    vector<int> a1, a2, a3, a4;
    for(int i=0; i<10; ++i)
    {
        int tmp;
        cout<<"please input: ";
        cin>>tmp;
        a1.push_back(tmp);
        a2.push_back(tmp);
        a3.push_back(tmp);
        a4.push_back(tmp);
    }
    insertionSort(a1);
    mergeSort(a2);
    quickSort(a3);
    bucketSort(a4);
    cout<<"insertion sort:"<<endl;
    for(int i=0; i!=a1.size(); ++i)
        cout<<" "<<a1[i];
    cout<<endl;
    cout<<"merge sort:"<<endl;
    for(int i=0; i!=a2.size(); ++i)
        cout<<" "<<a2[i];
    cout<<endl;
    cout<<"quick sort:"<<endl;
    for(int i=0; i!=a3.size(); ++i)
        cout<<" "<<a3[i];
    cout<<endl;
    cout<<"bucket sort:"<<endl;
    for(int i=0; i!=a4.size(); ++i)
        cout<<" "<<a4[i];
    cout<<endl;

测试结果：