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Major Updates in SinglyLinkedList.java #713

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Merged
merged 1 commit into from
Mar 9, 2019
Merged

Major Updates in SinglyLinkedList.java #713

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75 changes: 54 additions & 21 deletions DataStructures/Lists/SinglyLinkedList.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,11 +17,6 @@ class SinglyLinkedList {
*/
private Node head;

/**
* Count of nodes
*/
private int count;

/**
* This method inserts an element at the head
*
Expand All @@ -31,7 +26,6 @@ public void insertHead(int x) {
Node newNode = new Node(x);
newNode.next = head;
head = newNode;
++count;
}

/**
Expand All @@ -42,35 +36,51 @@ public void insertHead(int x) {
*/

public void insertNth(int data, int position) {
if (position < 0 || position > count) {
if (position < 0 || position > getSize()) {
throw new RuntimeException("position less than zero or position more than the count of list");
}
Node node = new Node(data);
Node dummy = new Node(-1);
dummy.next = head;
Node cur = dummy;
for (int i = 0; i < position; ++i) {
cur = cur.next;
else if (position == 0)
insertHead(data);
else {
Node cur = head;
Node node = new Node(data);
for (int i = 1; i < position; ++i) {
cur = cur.next;
}
node.next = cur.next;
cur.next = node;
}
node.next = cur.next;
cur.next = node;
++count;
}

/**
* This method deletes an element at the head
*
* @return The element deleted
*/
public Node deleteHead() {
public void deleteHead() {
if (isEmpty()) {
throw new RuntimeException("The list is empty!");
}

Node temp = head;
head = head.next;
--count;
return temp;
}

/**
* This method deletes an element at Nth position
*/
public void deleteNth(int position) {
if (position < 0 || position > getSize()) {
throw new RuntimeException("position less than zero or position more than the count of list");
}
else if (position == 0)
deleteHead();
else {
Node cur = head;
for (int i = 1; i < position; ++i) {
cur = cur.next;
}
cur.next = cur.next.next;
}
}

/**
Expand All @@ -79,7 +89,7 @@ public Node deleteHead() {
* @return true is list is empty
*/
public boolean isEmpty() {
return count == 0;
return getSize() == 0;
}

/**
Expand All @@ -94,6 +104,23 @@ public void display() {
System.out.println();
}

/**
* Returns the size of the linked list
*/
public int getSize() {
if (head == null)
return 0;
else {
Node current = head;
int size = 1;
while (current.next != null) {
current = current.next;
size++;
}
return size;
}
}

/**
* Main method
*
Expand All @@ -117,6 +144,11 @@ public static void main(String args[]) {
myList.insertNth(11, 2);

myList.display(); // 7 -> 5 -> 11

myList.deleteNth(1);

myList.display(); // 7-> 11

}
}

Expand Down Expand Up @@ -145,5 +177,6 @@ class Node {
*/
Node(int value) {
this.value = value;
this.next = null;
}
}