/***************************************************************
* Name: Rafael Orta
* Course: Computer Science & Programming
* Class: PDS04225
* Assignment Date: 04/17/22
* File Name: Radix-Sort.cpp
*****************************************************************
* Purpose: Demonstrate the implementation of Radix-Sort using C++
*****************************************************************/
#include <iostream>
using namespace std;
// A utility function to get maximum value in arr[]
int getMax(int[], int);
// A function to do counting sort of arr[] according to
// the digit represented by exp.
void countSort(int[], int, int);
// The main function to that sorts arr[] of size n using
// Radix Sort
void radixsort(int[], int);
// A utility function to print an array
void print(int[], int);
// Driver Code
int main()
{
int arr[] = { 170, 45, 75, 90, 802, 24, 2, 66 };
cout << "Array before sorting: " << endl;
print(arr,8);
int n = sizeof(arr) / sizeof(arr[0]);
// Function Call
radixsort(arr, n);
cout << "\nArray after sorting: " << endl;
print(arr, n);
return 0;
}
// A utility function to get maximum value in arr[]
int getMax(int arr[], int n)
{
int mx = arr[0];
for (int i = 1; i < n; i++)
if (arr[i] > mx)
mx = arr[i];
return mx;
}
// A function to do counting sort of arr[] according to
// the digit represented by exp.
void countSort(int arr[], int n, int exp)
{
int output[n]; // output array
int i, count[10] = { 0 };
// Store count of occurrences in count[]
for (i = 0; i < n; i++)
count[(arr[i] / exp) % 10]++;
// Change count[i] so that count[i] now contains actual
// position of this digit in output[]
for (i = 1; i < 10; i++)
count[i] += count[i - 1];
// Build the output array
for (i = n - 1; i >= 0; i--) {
output[count[(arr[i] / exp) % 10] - 1] = arr[i];
count[(arr[i] / exp) % 10]--;
}
// Copy the output array to arr[], so that arr[] now
// contains sorted numbers according to current digit
for (i = 0; i < n; i++)
arr[i] = output[i];
}
// The main function to that sorts arr[] of size n using
// Radix Sort
void radixsort(int arr[], int n)
{
// Find the maximum number to know number of digits
int m = getMax(arr, n);
// Do counting sort for every digit. Note that instead
// of passing digit number, exp is passed. exp is 10^i
// where i is current digit number
for (int exp = 1; m / exp > 0; exp *= 10)
countSort(arr, n, exp);
}
// A utility function to print an array
void print(int arr[], int n)
{
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
}
