1class Node {
2  constructor(val) {
3    this.data = val;
4    this.next = null;
5  }
6}
7
8class CircularLinkedList {
9  constructor() {
10    this.head = null;
11  }
12  addLast(val) {
13    const newNode = new Node(val);
14    if (!this.head) {
15      this.head = newNode;
16      this.head.next = this.head;
17      return;
18    }
19    let currentHead = this.head;
20    let current = this.head;
21    while (current.next !== currentHead) {
22      current = current.next;
23    }
24    newNode.next = currentHead;
25    current.next = newNode;
26  }
27  size() {
28    let count = 0;
29    let currentHead = this.head;
30    let current = this.head;
31    while (count === 0 || current !== currentHead) {
32      count++;
33      console.log(current.data);
34      current = current.next;
35    }
36    return count;
37  }
38  print() {
39    let count = 0;
40
41    let current = this.head;
42    while (count === this.size()) {
43      count++;
44      console.log(current.data);
45      current = current.next;
46    }
47  }
48  deleteFromLinkedList(val) {
49    if (!this.head) return;
50
51    let current = this.head;
52    let prev = null;
53    let found = false;
54
55    do {
56      if (current.data === val) {
57        found = true;
58        break;
59      }
60      prev = current;
61      current = current.next;
62    } while (current !== this.head);
63
64    if (!found) return;
65
66    if (this.head === this.head.next && this.head.data === val) {
67      this.head = null;
68      return;
69    }
70
71    if (current === this.head) {
72      prev = this.head;
73      while (prev.next !== this.head) {
74        prev = prev.next;
75      }
76      this.head = this.head.next;
77      prev.next = this.head;
78    } else {
79      prev.next = current.next;
80    }
81  }
82}
83
84let linkedList = new CircularLinkedList();
85linkedList.addLast('1');
86linkedList.addLast('2');
87linkedList.addLast('3');
88linkedList.addLast('4');
89linkedList.print();
90console.log('<====>');
91// console.log(linkedList.head)
92
93linkedList.deleteFromLinkedList('1');
94linkedList.print();
95