Add solution #1670

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,462 LeetCode solutions in JavaScript
+# 1,463 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1286,6 +1286,7 @@
 1665|[Minimum Initial Energy to Finish Tasks](./solutions/1665-minimum-initial-energy-to-finish-tasks.js)|Hard|
 1668|[Maximum Repeating Substring](./solutions/1668-maximum-repeating-substring.js)|Easy|
 1669|[Merge In Between Linked Lists](./solutions/1669-merge-in-between-linked-lists.js)|Medium|
+1670|[Design Front Middle Back Queue](./solutions/1670-design-front-middle-back-queue.js)|Medium|
 1672|[Richest Customer Wealth](./solutions/1672-richest-customer-wealth.js)|Easy|
 1679|[Max Number of K-Sum Pairs](./solutions/1679-max-number-of-k-sum-pairs.js)|Medium|
 1716|[Calculate Money in Leetcode Bank](./solutions/1716-calculate-money-in-leetcode-bank.js)|Easy|

solutions/1670-design-front-middle-back-queue.js

@@ -0,0 +1,76 @@
+/**
+ * 1670. Design Front Middle Back Queue
+ * https://leetcode.com/problems/design-front-middle-back-queue/
+ * Difficulty: Medium
+ *
+ * Design a queue that supports push and pop operations in the front, middle, and back.
+ *
+ * Implement the FrontMiddleBack class:
+ * - FrontMiddleBack() Initializes the queue.
+ * - void pushFront(int val) Adds val to the front of the queue.
+ * - void pushMiddle(int val) Adds val to the middle of the queue.
+ * - void pushBack(int val) Adds val to the back of the queue.
+ * - int popFront() Removes the front element of the queue and returns it. If the queue is
+ *   empty, return -1.
+ * - int popMiddle() Removes the middle element of the queue and returns it. If the queue is
+ *   empty, return -1.
+ * - int popBack() Removes the back element of the queue and returns it. If the queue is
+ *   empty, return -1.
+ *
+ * Notice that when there are two middle position choices, the operation is performed on the
+ * frontmost middle position choice. For example:
+ * - Pushing 6 into the middle of [1, 2, 3, 4, 5] results in [1, 2, 6, 3, 4, 5].
+ * - Popping the middle from [1, 2, 3, 4, 5, 6] returns 3 and results in [1, 2, 4, 5, 6].
+ */
+
+var FrontMiddleBackQueue = function() {
+  this.elements = [];
+};
+
+/**
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushFront = function(val) {
+  this.elements.unshift(val);
+};
+
+/**
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushMiddle = function(val) {
+  const mid = Math.floor(this.elements.length / 2);
+  this.elements.splice(mid, 0, val);
+};
+
+/**
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushBack = function(val) {
+  this.elements.push(val);
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popFront = function() {
+  return this.elements.length ? this.elements.shift() : -1;
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popMiddle = function() {
+  if (!this.elements.length) return -1;
+  const mid = Math.floor((this.elements.length - 1) / 2);
+  return this.elements.splice(mid, 1)[0];
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popBack = function() {
+  return this.elements.length ? this.elements.pop() : -1;
+};