distribution counting—a sorting method from aocp

/*
*From the art of computer programming:vol 3:Sorting and Searching
*时间：2012年3月6日21:02:32
*作者：张超
*Email:uestczhangchao@gmail.com
*/

#include <iostream> 

using namespace std; 
void Distribution_Counting(int array[], int arraylen)
{
    int *tmp = new int[arraylen];
    int *count = NULL;
    int i,j;
    int minvalue=INT_MAX, maxvalue=INT_MIN;
    int valuescope;
    memset(tmp,0,sizeof(int)*arraylen);

    
    for (i=0; i<arraylen; i++)
    {
        if (array[i]<minvalue)
        {
             minvalue=array[i];
        }
        if (array[i]>maxvalue)
        {
            maxvalue = array[i];
        }
        
    }

    valuescope = maxvalue-minvalue+1;
    count = new int[valuescope];


    memset(count,0,sizeof(int)*valuescope);
    

    //统计array内的数字在minvalue和maxvalue范围的出现次数
    for (i=0; i<arraylen; i++)
    {
        count[array[i]-minvalue]++;
    }

    //统计minvalue和maxvalue范围内，不小于该范围内某个数的出现频数
    //count[i]对应小于value+i的数出现的次数
    for (i=1; i<valuescope; i++)
    {
        count[i] = count[i] + count[i-1];
    }

    //依次输出每个数字，输出的顺序为non-descending顺序，并且保证是有序的
    for (j=arraylen-1;j>=0;j--)
    {
        ////取出该关键字出现的次数
        i = count[array[j]-minvalue];
        tmp[i-1] = array[j];
        --count[array[j]-minvalue];

    }

    //将结果拷贝到array数组中
    for (i=0; i<arraylen; i++)
    {
        array[i] = tmp[i];
    }

    delete []tmp;
    delete []count;

}


int main()
{
    int data[] = {8,5,4,5,6,10};
    int size = sizeof(data)/sizeof(int);
    Distribution_Counting(data,size);
    for(int i=0; i<size;i++)
    {
        cout <<" " << data[i] << " ";
    }
    cout << endl;

    return 0;
}