计数排序与基数排序

 1 void countingSort(array<int> &a, int k) //a中皆为整数，范围为0到K-1
 2 {
 3     array<int> c(k, 0);
 4     for (int i = 0; i < a.length; ++i)
 5         c[a[i]]++;
 6     for (int j = 1; j < k; j++)
 7         c[j] = c[j] + c[j-1];
 8     array<int> b(a.length);
 9     for (int i = a.length-1; i >= 0; --i)
10         b[--c[a[i]]] = a[i];
11     a = b;
12 }

 1 void radixSort(array<int> &a)
 2 {
 3     int d = 8, w = 32;
 4     for (int p = 0; p < w/d; p++)
 5     {
 6         array<int> c(1 << d, 0);
 7         array<int> b(a.length);
 8         for (int i = 0; i < a.length; i++)
 9             c[(a[i] >> d*p) & ((1<<d) - 1)]++;
10         for (int j = 1; j < 1<<d; j++)
11             c[j] += c[j-1];
12         for (int i = a.length - 1; i >= 0; i--)
13             b[--c[ (a[i] >> d*p) & ( (1<<d) - 1 ) ]] = a[i];
14         a = b;
15     }
16 }