Create 1670-design-front-middle-back-queue.js

Author: everthis

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

@@ -0,0 +1,68 @@
+
+const FrontMiddleBackQueue = function() {
+  this.arr = []
+};
+
+/** 
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushFront = function(val) {
+  this.arr.unshift(val)
+};
+
+/** 
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushMiddle = function(val) {
+  const len = this.arr.length
+  const mid = Math.floor(len / 2)
+  this.arr.splice(mid, 0, val)
+};
+
+/** 
+ * @param {number} val
+ * @return {void}
+ */
+FrontMiddleBackQueue.prototype.pushBack = function(val) {
+  this.arr.push(val)
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popFront = function() {
+  const tmp = this.arr.shift()
+  return tmp == null ? -1 : tmp
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popMiddle = function() {
+  const len = this.arr.length
+  const mid = len % 2 === 0 ? Math.floor(len / 2) - 1 : ((len / 2) >> 0)
+  if(len === 2) return this.arr.shift()
+  const [tmp] = this.arr.splice(mid, 1)
+  return tmp == null ? -1 : tmp
+};
+
+/**
+ * @return {number}
+ */
+FrontMiddleBackQueue.prototype.popBack = function() {
+  const tmp = this.arr.pop()
+  return tmp == null ? -1 : tmp
+};
+
+/** 
+ * Your FrontMiddleBackQueue object will be instantiated and called as such:
+ * var obj = new FrontMiddleBackQueue()
+ * obj.pushFront(val)
+ * obj.pushMiddle(val)
+ * obj.pushBack(val)
+ * var param_4 = obj.popFront()
+ * var param_5 = obj.popMiddle()
+ * var param_6 = obj.popBack()
+ */