基于计数排序子程序的基数排序实现

#include "stdafx.h"
#include <iostream>
#include <math.h>
using namespace std;

#define RADIX 3
#define LENGTH 7

int A[LENGTH] = { 329, 457, 657, 839, 436, 720, 355 };

// copy a[] into b[]
void CopyArray(int* a, int* b)
{
for (int i = 0; i < LENGTH; ++i) {
b[i] = a[i];
}
}

void PrintArray(int* a)
{
for (int i = 0; i < LENGTH; ++i) {
cout << a[i] << " ";
}
cout << endl;
}

//返回整型a的第i位数
//GetDigitI(790,3) = 7
//GetDigitI(790,2) = 9
//GetDigitI(790, 1) = 0
int GetDigitI(int a, int i)
{
return (a / (int)pow(10, i-1)) % 10;
}

//计数排序
void CountingSort(int* a, int i)
{
int B[LENGTH] = { 0 }; //存本次的排序结果
int C[10] = { 0 }; //用于统计的辅助数组
//统计第i位上的值出现次数
for (int k = 0; k < LENGTH; ++k) {
int t = GetDigitI(a[k], i);
C[t] += 1;
}
//累加
for (int k = 1; k < 10; ++k) {
C[k] = C[k] + C[k - 1];
}
//根据累加数组C,对a进行排序,结果在B中
for (int k = LENGTH-1; k >= 0; --k) {
int t = GetDigitI(a[k], i);
B[C[t] - 1] = a[k];
C[t] -= 1;
}
CopyArray(B,a);
}

//基数排序
void RadixSort()
{
int* t = A;
for (int i = 1; i <= RADIX; ++i) {
//Use Counting sort to sort array A on digit i
CountingSort(t, i);
cout << "Result " << i <<": \n";
PrintArray(A);
}
}

int _tmain(int argc, _TCHAR* argv[])
{
PrintArray(A);
RadixSort();
return 0;
}