Algorithmic Implementation series(8) Implementation of Counting_Sort

Compiler: gcc 4.7.3

C++ Standard: C++0x

OS: CentOS 6.3 x86

  1 #include <iostream>
  2 
  3 using namespace std;
  4 
  5 void Counting_Sort(unsigned uaa[], const size_t size_of_uaa,
  6                 unsigned uab[], const size_t k) {
  7 
  8     unsigned c[k + 1];
  9     for(size_t i = 0; i != k + 1; ++i) {
 10         c[i] = 0;
 11     }
 12     //c[i] now contains the number of elements equal to i.
 13     for(size_t j = 0; j != size_of_uaa; ++j) {
 14         ++c[uaa[j]];
 15     }
 16     //c[i] now contains the number of elements less than or equal to i.
 17     for(size_t i = 1; i != k + 1; ++i) {
 18         c[i] = c[i] + c[i - 1];
 19     }
 20 
 21     for(size_t j = size_of_uaa; j != 0; --j) {
 22         uab[c[uaa[j - 1]] - 1] = uaa[j - 1];
 23         --c[uaa[j - 1]];
 24     }
 25 }
 26 //Returning the elememt of which the value is max of the array.
 27 const unsigned max_element(unsigned ua[], const size_t size) {
 28     if(size == 1) {
 29         return ua[0];
 30     }
 31     unsigned max = 0;
 32 
 33     for(size_t i = 0; i != size; ++i) {
 34         if(max < ua[i]) {
 35             max = ua[i];
 36         }
 37     }
 38     return max;
 39 }
 40 
 41 int main() {
 42     unsigned uaa[] = {0, 4, 5, 33, 34, 6, 7, 8, 9, 12, 98, 99, 54, 23, 121, 1};                     
 43     const size_t size = sizeof(uaa)/sizeof(unsigned);
 44     unsigned uab[size];
 45 
 46     Counting_Sort(uaa, size, uab, max_element(uaa, size));
 47 
 48     for(auto beg = begin(uab); beg != end(uab); ++beg) {
 49         cout << *beg << " ";
 50     }
 51     cout << endl;
 52 
 53     return EXIT_SUCCESS;
 54 }