counting sort.cpp

#include <bits/stdc++.h>
#include <string.h>
using namespace std;
#define RANGE 255

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]];
    }
 
    for (i = 0; arr[i]; ++i)
        arr[i] = output[i];
}

int main()
{
    char arr[] = "geeksforgeeks";
  
    countSort(arr);
  
    cout << "Sorted character array is " << arr;
    return 0;
}