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radix_sort.java
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radix_sort.java
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import java.util.Arrays;
import java.util.Scanner;
public class radix_sort {
public static void main(String[] args) {
// import scanner to take user input
Scanner sc = new Scanner(System.in);
System.out.println("enter the size of the array");
int size = sc.nextInt();
System.out.println("enter the element in the array");
int[] arr = new int[size];
// store the inputed elements in the array
for(int i = 0; i<size; i++) {
arr[i] = sc.nextInt();
}
// call our sorting function
radixSort(arr);
System.out.println(Arrays.toString(arr));
}
public static void radixSort(int[] arr) {
// search for the maximum number to know the number of digits
int max = getMax(arr);
// do counting sort here
for (int exp = 1; max/exp > 0; exp *= 10) {
countingSort(arr, exp);
}
}
public static void countingSort(int[] arr, int exp) { // sort the array by each digit starting with the least significant digit in the array
int[] output = new int[arr.length]; // the final array in which we will store our answer
int[] count = new int[10]; // the counting array
// store all the counting occourences in count array
for (int i = 0; i < arr.length; i++) {
count[(arr[i]/exp)%10]++;
}
// change our element at count[i] to count[i-1] so that this contains actual position of the digit in output array
for (int i = 1; i < 10; i++) {
count[i] += count[i - 1];
}
// create our output array
for (int i = arr.length - 1; i >= 0; i--) {
output[count[(arr[i]/exp)%10] - 1] = arr[i];
count[(arr[i]/exp)%10]--;
}
// store the output array in our ans array, so that numbers that are sorted now can be stored
for (int i = 0; i < arr.length; i++) {
arr[i] = output[i];
}
}
// normal function to find the max value in our array
public static int getMax(int[] arr) {
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
if (arr[i] > max) {
max = arr[i];
}
}
return max;
}
}