排序补充（计数基数排序）

 1 void CountSort(int *a , size_t size)
 2 {
 3     int max = a[0], min = a[0];
 4     for (int i =1; i < size; ++i)
 5     {
 6         if (max < a[i])
 7         {
 8             max = a[i];
 9         }
10         if (min > a[i])
11         {
12             min = a[i];
13         }
14     }
15     int index = 0;
16     int *CountArray = new int[max - min + 1];
17     memset(CountArray, 0, sizeof(int)*(max - min + 1));
18     for (int i = 0; i < size; ++i)
19     {
20         CountArray[a[i] - min]++;
21     }
22     for (int i = 0; i < max - min + 1; ++i)
23     {
24         for (int j = 0; j < CountArray[i]; ++j)
25         {
26             a[index++] = i + min;
27         }
28     }
29 }

 1 int GetMaxDigit(int *a,size_t size)
 2 {
 3     int digit = 1;
 4     int max = 10;
 5     for (int i = 0; i < size; ++i)
 6     {
 7         while (a[i] >= max)
 8         {
 9             digit++;
10             max *= 10;
11         }
12     }
13     return digit;
14 }
15 
16 //一共需要几个数组呢？一个count,一个start还有一个收集用的暂存数组？最后拷贝回去就可以了！
17 void DigitSort(int *a, size_t size)
18 {
19     int MaxDigit = GetMaxDigit(a, size);
20     int curDigit = 1;
21     int digit = 0;
22     int Count[10];
23     int Start[10];
24     int *Bucket = new int[size];
25     while (digit < MaxDigit)
26     {
27         memset(Count, 0, sizeof(int) * 10);
28         memset(Start, 0, sizeof(int) * 10);
29         for (int i = 0; i < size; ++i)
30         {
31             int num = a[i] / curDigit % 10;
32             Count[num]++;
33         }
34         Start[0] = 0;
35         for (int i = 1; i < 10; ++i)
36         {
37             Start[i] = Start[i - 1] + Count[i - 1];
38         }
39         for (int i = 0; i < size; ++i)
40         {
41             int num = a[i] / curDigit % 10;
42             Bucket[Start[num]++] = a[i];
43         }
44         memcpy(a, Bucket, sizeof(int)*size);
45         digit++;
46         curDigit *= 10;
47     }
48 }