C Program for Counting Sort
Counting sort is a sorting technique based on keys between a specific range. It works by counting the number of objects having distinct key values (kind of hashing). Then doing some arithmetic to calculate the position of each object in the output sequence.
C
// C Program for counting sort #include <stdio.h> #include <string.h> #define RANGE 255 // The main function that sort the given string arr[] in // alphabetical order void countSort( char arr[]) { // The output character array that will have sorted arr char output[ strlen (arr)]; // Create a count array to store count of individual // characters and initialize count array as 0 int count[RANGE + 1], i; memset (count, 0, sizeof (count)); // Store count of each character for (i = 0; arr[i]; ++i) ++count[arr[i]]; // Change count[i] so that count[i] now contains actual // position of this character in output array for (i = 1; i <= RANGE; ++i) count[i] += count[i-1]; // Build the output character array for (i = 0; arr[i]; ++i) { output[count[arr[i]]-1] = arr[i]; --count[arr[i]]; } // Copy the output array to arr, so that arr now // contains sorted characters for (i = 0; arr[i]; ++i) arr[i] = output[i]; } // Driver program to test above function int main() { char arr[] = "geeksforgeeks" ; //"applepp"; countSort(arr); printf ( "Sorted character array is %sn" , arr); return 0; } |
Output:
Sorted character array is eeeefggkkorssn
Please refer complete article on Counting Sort for more details!