package me.ramswaroop.linkedlists;
import me.ramswaroop.common.SingleLinkedList;
import me.ramswaroop.common.SingleLinkedNode;
import java.util.HashMap;
import java.util.Map;
/**
* Created by IntelliJ IDEA.
*
* @author: ramswaroop
* @date: 6/18/15
* @time: 2:35 PM
*/
public class RemoveDuplicates {
/**
* Removes duplicates from a sorted linked list
* by traversing it once.
*
* @param list
* @param <E>
*/
public static <E extends Comparable<E>> void removeDuplicates(SingleLinkedList<E> list) {
SingleLinkedNode<E> curr = list.getNode(0);
int index = 0;
while (curr != null) {
// inner while loop for removing multiple duplicates
while (curr.next != null && curr.item == curr.next.item) {
list.remove(index + 1);
}
index++;
curr = curr.next;
}
}
/**
* Removes duplicates from an unsorted linked list.
* <p/>
* This method uses {@link java.util.HashMap}, another
* way is that you can sort it using merge sort and then
* call {@link #removeDuplicates}.
*
* @param list
* @param <E>
*/
public static <E extends Comparable<E>> void removeDuplicatesFromUnsortedList(SingleLinkedList<E> list) {
SingleLinkedNode<E> curr = list.getNode(0);
Map<E, Boolean> map = new HashMap<>();
int index = 0;
while (curr != null) {
if (map.get(curr.item) == null) {
map.put(curr.item, true);
index++;
} else {
list.remove(index);
}
curr = curr.next;
}
}
public static void main(String a[]) {
SingleLinkedList<Integer> linkedList = new SingleLinkedList<>();
linkedList.add(00);
linkedList.add(00);
linkedList.add(00);
linkedList.add(11);
linkedList.add(11);
linkedList.add(22);
linkedList.add(22);
linkedList.add(22);
linkedList.add(22);
linkedList.add(33);
linkedList.add(33);
linkedList.add(33);
linkedList.add(33);
linkedList.printList();
removeDuplicates(linkedList);
linkedList.printList();
SingleLinkedList<Integer> linkedList2 = new SingleLinkedList<>();
linkedList2.add(00);
linkedList2.add(00);
linkedList2.add(22);
linkedList2.add(11);
linkedList2.add(44);
linkedList2.add(22);
linkedList2.add(66);
linkedList2.add(77);
linkedList2.add(66);
linkedList2.printList();
removeDuplicatesFromUnsortedList(linkedList2);
linkedList2.printList();
}
}