counting sort algorithm

// C++ Program for counting sort 
#include <bits/stdc++.h> 
using namespace std; 

  
// The main function that sort 
// the given string arr[] in 
// alphabatical 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 inidividul 
    // 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]]; 
    } 
  
    /*  
    For Stable algorithm  
    for (i = sizeof(arr)-1; i>=0; --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  code 
int main() 
{ 
    char arr[] = "geeksforgeeks"; 
  
    countSort(arr); 
  
    cout << "Sorted character array is " << arr; 
    return 0; 
}