Queue with stacks

.eslintrc.json

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+{
+    "env": {
+      "browser": true,
+      "node": true,
+      "commonjs": true,
+      "jest": true,
+      "es6": true
+    },
+    "globals": {
+      "err": true,
+      "req": true,
+      "res": true,
+      "next": true
+    },
+    "extends": "eslint:recommended",
+    "parserOptions": {
+      "sourceType": "module"
+    },
+    "rules": {
+      "no-console": "off",
+      "indent": [ "error", 2 ],
+      "quotes": ["error", "single", { "allowTemplateLiterals": true }],
+      "comma-dangle": ["error", "always-multiline"],
+      "semi": [ "error", "always" ]
+    }
+  }
+

README.md

@@ -1,6 +1,15 @@
-# Table of Contents
-[1- code challange class 2 array shift ](https://github.com/Goorob-401-advanced-javascript/data-structures-and-algorithms/pull/3)
+# Queue-with-stacks 
+## challange summary 
 
-[2- code challange class 3 array binary search ](https://github.com/Goorob-401-advanced-javascript/data-structures-and-algorithms/pull/2)
+Implement a Queue using two Stacks.
 
-[
+## Challenge description
+Create a brand new PseudoQueue class , this PseudoQueue class will implement our standard queue , but will internally only utilize 2 Stack objects. 
+- enqueue(value) which inserts value into the PseudoQueue, using a first-in, first-out approach.
+- dequeue() which extracts a value from the PseudoQueue, using a first-in, first-out approach.
+
+## Approach & Efficiency
+only take up O(1) at most and for space it should be O(n) .
+
+## Solution
+![UML](https://github.com/Goorob-401-advanced-javascript/data-structures-and-algorithms/blob/queue-with-stacks/20200210_141653.jpg)

challanges/queue-with-stacks/queue-with-stack.js

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+'use strict';
+
+class PsuedoQueue {
+
+  constructor(){
+
+    this.stack_1 = [];
+    this.stack_2 = [];
+
+  }
+  enqueue(value){
+    this.stack_1.push(value);
+  }
+  dequeue(){
+    if(this.stack_1.length === 0){
+      return 'null';
+    } while (this.stack_1.length > 0) {
+      let popFromStack = this.stack_1.pop();
+      this.stack_2.push(popFromStack);
+    }
+
+    while(this.stack_2.length > 0){
+      let popFromStack = this.stack_2.pop();
+      this.stack_1.push(popFromStack);
+    }
+    return this.stack_2.pop();
+  }
+}
+module.exports = PsuedoQueue;

challanges/queue-with-stacks/queue-with-stacks.test.js

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+'use strict';
+const PseudoQueue = require('./queue-with-stack.js');
+let pseudoQueue = new PseudoQueue();
+
+describe('Testing queue-with-stacks', () => {
+  beforeEach(() => {
+    pseudoQueue = new PseudoQueue();
+  });
+  it('Enqueue values', () => {
+    pseudoQueue.enqueue('301');
+    pseudoQueue.enqueue('401');
+    expect(pseudoQueue.stack_1).toEqual(['301', '401']);
+  });
+  it('Dequeue values', () => {
+    pseudoQueue.enqueue('301');
+    pseudoQueue.enqueue('401');
+    pseudoQueue.dequeue();
+    expect(pseudoQueue.stack_1).toEqual(['301' ,'401']);
+  });
+});