LF.319.Delete Node At Index

Delete the node at the given index for the given linked list.

Examples

[1, 2, 3], delete at 1 --> [1, 3]

[1, 2, 3], delete at 4 --> [1, 2, 3]

[1, 2, 3], delete at 0 --> [2, 3]

public class Solution {
  public ListNode deleteNode(ListNode head, int index) {
    // Write your solution here
    //corner case
    if (head == null || index < 0) {
        return head ;
    }
    int length = getLength(head) ;
    //corner case
    if (length < index +1 ) {
        return head ;
    }
    ListNode dummy = new ListNode(0);
    dummy.next = head ;
    ListNode curr = dummy ;
    int counter = 0 ;
    /*
            [1, 2, 3], delete at 1 --> [1, 3]
    d/c----->         counter = 0
             c-->     counter = 1
    */
    while(curr != null && curr.next != null){
        if (counter == index) {
            curr.next = curr.next.next ;
            break ;
        }
        curr = curr.next ;
        counter++;
    }
    return dummy.next ;
  }
  private int getLength(ListNode head){
    if (head == null) {
        return 0;
    }
    ListNode curr = head ;
    int res = 0 ;
    while(curr != null){
        curr = curr.next ;
        res++;
    }
    return res ;
  }
}