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The full LinkedList implementation from this tutorial: https://bit.ly/2mihZac
class LinkedListNode {
constructor(value, next) {
this.value = value;
this.next = next || null;
}
}
class LinkedList {
constructor(value) {
this.size = 0;
this.head = null;
this.tail = null;
if (value) {
if (Array.isArray(value)) return this.fromArray(value);
return new TypeError(value + ' is not iterable');
};
return this;
}
prepend(value) {
this.size += 1;
const newNode = new LinkedListNode(value, this.head);
this.head = newNode;
if (!this.tail) this.tail = newNode;
return this;
}
append(value) {
this.size += 1;
const newNode = new LinkedListNode(value);
if (!this.head) {
this.head = newNode;
this.tail = newNode;
return this;
}
this.tail.next = newNode;
this.tail = newNode;
return this;
}
fromArray(values) {
values.forEach(value => this.append(value));
return this;
}
toArray(useNodes = false) {
const nodes = [];
let currentNode = this.head;
while (currentNode) {
nodes.push(useNodes ? currentNode : currentNode.value);
currentNode = currentNode.next;
};
return nodes;
}
includes(value) {
if (!this.head) return false;
let isNode = value.constructor.name === 'LinkedListNode';
if (isNode) value = value.value;
let currentNode = this.head;
while (currentNode) {
if (value !== undefined && value === currentNode.value) {
return true;
};
currentNode = currentNode.next;
};
return false;
}
find(callback) {
if (Object.prototype.toString.call(callback) !== '[object Function]') {
return new TypeError(callback + ' is not a function');
};
if (!this.head) return undefined;
let currentNode = this.head;
while (currentNode) {
if (callback && callback(currentNode.value)) {
return currentNode;
};
currentNode = currentNode.next;
};
return undefined;
}
delete(value, deleteOne = false) {
if (!this.head) return false;
let deletedNode = null;
// If the head needs to be deleted
while (this.head && this.head.value === value) {
this.size -= 1;
deletedNode = this.head;
this.head = this.head.next;
if (deleteOne) return true;
};
let currentNode = this.head;
// If any node except the head or tail needs to be deleted
if (currentNode !== null) {
while (currentNode.next) {
if (currentNode.next.value === value) {
this.size -= 1;
deletedNode = currentNode.next;
currentNode.next = currentNode.next.next;
if (deleteOne) return true;
} else {
currentNode = currentNode.next;
};
};
};
// If the tail needs to be deleted
if (this.tail.value === value) {
this.tail = currentNode;
};
if (deletedNode === null) {
return false;
} else {
return true;
};
}
deleteHead() {
if (!this.head) return null;
this.size -= 1;
const deletedHead = this.head;
if (this.head.next) {
this.head = this.head.next;
} else {
this.head = null;
this.tail = null;
}
return deletedHead;
}
deleteTail() {
if (this.size === 0) return false;
if (this.size === 1) {
if (this.head === null) {
return false;
} else {
this.head = null;
this.tail = null;
this.size -= 1;
return true;
}
}
const deletedTail = this.tail;
let currentNode = this.head;
while (currentNode.next) {
if (!currentNode.next.next) {
this.size -= 1;
currentNode.next = null;
} else {
currentNode = currentNode.next;
}
}
this.tail = currentNode;
return deletedTail;
}
}
module.exports = LinkedList
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