Radix Sort Java Program Logic




Hey guys in this post, we will discuss the most popular sorting algorithm that is Radix sort in Java language.

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import java.util.Arrays;

class RadixSort {

	// A utility function to get maximum value in arr[]
	static 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.
	static void countSort(int arr[], int n, int exp)
	{
		int output[] = new int[n]; // output array
		int i;
		int count[] = new int[10];
		Arrays.fill(count,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 curent digit
		for (i = 0; i < n; i++)
			arr[i] = output[i];
	}

	// The main function to that sorts arr[] of size n using
	// Radix Sort
	static 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
	static void print(int arr[], int n)
	{
		for (int i=0; i<n; i++)
			System.out.print(arr[i]+" ");
	}


	/*Driver function to check for above function*/
	public static void main (String[] args)
	{
		int arr[] = {170, 45, 75, 90, 802, 24, 2, 66};
		int n = arr.length;
		radixsort(arr, n);
		print(arr, n);
	}
}

Output:

2 24 45 66 75 90 170 802 

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Bushan Sirgur

Hey guys, I am Bushan Sirgur from Banglore, India. Currently, I am working as an Associate project in an IT company.

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