124.cpp

#include<iostream>
using namespace std;

// A function to do counting sort of arr[] according to
// the digit represented by exp.
int countSort(int arr[], int n, int exp)
{

	int output[n]; // output array
	int i, count[n] ;
	for (int i=0; i < n; i++)
	count[i] = 0;

	// Store count of occurrences in count[]
	for (i = 0; i < n; i++)
		count[ (arr[i]/exp)%n ]++;

	// Change count[i] so that count[i] now contains actual
	// position of this digit in output[]
	for (i = 1; i < n; i++)
		count[i] += count[i - 1];

	// Build the output array
	for (i = n - 1; i >= 0; i--)
	{
		output[count[ (arr[i]/exp)%n] - 1] = arr[i];
		count[(arr[i]/exp)%n]--;
	}

	// 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 sort(int arr[], int n)
{
	// Do counting sort for first digit in base n. Note that
	// instead of passing digit number, exp (n^0 = 1) is passed.
	countSort(arr, n, 1);

	// Do counting sort for second digit in base n. Note that
	// instead of passing digit number, exp (n^1 = n) is passed.
	countSort(arr, n, n);
}

// A utility function to print an array
void printArr(int arr[], int n)
{
	for (int i = 0; i < n; i++)
		cout << arr[i] << " ";
}

// Driver program to test above functions
int main()
{
	// Since array size is 7, elements should be from 0 to 48
	int arr[] = {40, 12, 45, 32, 33, 1, 22};
	int n = sizeof(arr)/sizeof(arr[0]);
	cout << "Given array is n";
	printArr(arr, n);

	sort(arr, n);

	cout << "nSorted array is n";
	printArr(arr, n);
	return 0;
}