Design Linked List LeetCode solution in Java

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class MyLinkedList {
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  public class ListNode {
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    public int val;
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    public ListNode next;
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    public ListNode() {}
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    public ListNode(int val) {
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      this.val = val;
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    }
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    public ListNode(int val, ListNode next) {
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      this.val = val;
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      this.next = next;
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    }
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  }
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  private ListNode head;
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  private ListNode tail;
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  private int length;
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  public MyLinkedList() {
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    length = 0;
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  }
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  public int get(int index) {
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    if (index > length - 1 || index < 0) return -1;
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    int thisIndex = 0;
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    ListNode temp = head;
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    while (thisIndex != index) {
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      temp = temp.next;
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      thisIndex++;
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    }
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    return temp.val;
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  }
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  public void addAtHead(int val) {
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    head = new ListNode(val, head);
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    length++;
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    if (length == 1) tail = head;
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  }
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  public void addAtTail(int val) {
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    length++;
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    if (length == 1) {
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      ListNode onlyNode = new ListNode(val);
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      head = onlyNode;
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      tail = head;
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      return;
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    }
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    tail.next = new ListNode(val);
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    tail = tail.next;
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  }
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  public void addAtIndex(int index, int val) {
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    if (index <= length) {
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      if (index == 0) {
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        addAtHead(val);
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        return;
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      }
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      if (index == length) {
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        addAtTail(val);
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        return;
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      }
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      length++;
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      ListNode temp = head;
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      int thisIndex = 0;
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      while (thisIndex != index - 1) {
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        temp = temp.next;
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        thisIndex++;
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      }
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      temp.next = new ListNode(val, temp.next);
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    }
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  }
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  public void deleteAtIndex(int index) {
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    if (index >= length || index < 0) return;
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    length--;
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    if (index == 0) {
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      head = head.next;
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      return;
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    }
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    ListNode temp = head;
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    int thisIndex = 0;
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    while (thisIndex != index - 1) {
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      temp = temp.next;
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      thisIndex++;
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    }
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    if (index == length) {
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      tail = temp;
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      temp.next = null;
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    } else temp.next = temp.next.next;
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  }
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}