数据结构基础(1) --Swap ; Bubble-Sort ； Select-Sort

//C语言方式(by-pointer):  
template <typename Type>  
bool swapByPointer(Type *pointer1, Type *pointer2)  
{  
    //确保两个指针不会指向同一个对象  
    if (pointer1 == NULL || pointer2 == NULL)  
    {  
        return false;  
    }  
    if (pointer1 != pointer2)  
    {  
        Type tmp = *pointer1;  
        *pointer1 = *pointer2;  
        *pointer2 = tmp;  
    }  
    return true;  
}  

//C++特有方式(by-reference):  
template <typename Type>  
void swapByReference(Type &value1, Type &value2)  
{  
    if (value2 != value1)  
    {  
        Type tmp = value1;  
        value1 = value2;  
        value2 = tmp;  
    }  
}  

//实现:注意代码中的三个注意点(x):  
template <typename Type>  
void bubbleSort(Type *begin, Type *end)  
{  
    if ((begin == end) || (begin == NULL) || (end == NULL))  
        return ;  
    int length = end - begin;  
    //注意点(1):保证一旦数组有序, 则会直接停止排序, 不会在继续进行无用的循环  
    bool isOrder = false;  
    //外层循环控制扫描次数(length-1)  
    //注意点(2):N个元素其实只需N-1次扫描  
    for (int i = 0; !isOrder && i < length-1; ++i)  
    {  
        //首先假定这次数组已经有序  
        isOrder = true;  
        //注意点(3):确保能够从0扫描到最后一个未排序的元素  
        for (Type *iter = begin; iter < end-i-1; ++iter)  
        {  
            //如果前面的左边的元素>右边的元素  
            if (*iter > *(iter+1))  
            {  
                //交换  
                std::swap(*iter, *(iter+1));  
                isOrder = false;  
            }  
        }  
    }  
}  
template <typename Type>  
void bubbleSort(Type *array, int length)  
{  
    return bubbleSort(array, array+length);  
}  

//实现  
template <typename Type>  
void selectSort(Type *begin, Type *end)  
{  
    if ((begin == end) || (begin == NULL) || (end == NULL))  
        return ;  
    //只要循环到最后一个元素的前一个就行了,因为剩下的那个肯定是最大的  
    for (Type *outer = begin; outer < end-1; ++outer)  
    {  
        //注意:是从尚未排序的序列中查找(miner = outer, inner = outer+1)  
        Type *miner = outer;  
        //从miner+1开始遍历数组, 寻找一个元素值小于*miner的  
        for (Type *inner = outer+1; inner < end; ++inner)  
        {  
            if (*inner < *miner)  
                miner = inner;  
        }  
        if (miner != outer)  
            std::swap(*miner, *outer);  
    }  
}  
//为了能够让STL的标准容器如vector使用  
template <typename Iterator>  
void selectSort(Iterator iter1, Iterator iter2)  
{  
    return selectSort(&(*iter1), &(*iter2));  
}  
template <typename Type>  
void selectSort(Type *array, int length)  
{  
    return selectSort(array, array+length);  
}  

int main()  
{  
    srand(time(NULL));  
    vector<double> dVec;  
    int count = 10;  
    while (count --)  
    {  
        dVec.push_back((rand()%1000)/100.0);  
    }  
    selectSort(dVec.begin(), dVec.end());  
    for (vector<double>::iterator iter = dVec.begin(); iter < dVec.end(); ++iter)  
    {  
        cout << *iter << endl;  
    }  
    return 0;  
}