Topics
Linked List

Reverse Linked List (opens in a new tab)

  • Iterating through the list and reversing the direction of the next pointers of the nodes.
  • After the entire list is reversed, the head pointer is updated to point to the new head of the list, which was the original tail.
/**
/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var reverseList = function(head) {
    let prev = null,curr=head,next=null
    while(curr!=null){
        next = curr.next;
        curr.next = prev;
        prev = curr;
        curr = next;
    }
    head = prev;
    return head;
};
Complexity
  • Time: O(n)
  • Space: O(1)

Delete Node in a Linked List (opens in a new tab)

  • Copy the data from the successor node into the current node to be deleted.
  • Update the next pointer of the current node to reference the next pointer of the successor node.
/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} node
 * @return {void} Do not return anything, modify node in-place instead.
 */
var deleteNode = function(node) {
node.val=node.next.val;
node.next=node.next.next;
};
Complexity
  • Time: O(1)
  • Space: O(1)
HeapGreedy