Add day 39

Author: MadhavBahl

README.md

@@ -66,6 +66,7 @@ Motivate yourself to code daily till 60 days, and see the magic! Coding will bec
 | [Day 36](./day36) | [Radix Sort](./day36) | [http://codetoexpress.tech/dc/day36/](http://codetoexpress.tech/dc/day36/) | **Intermediate** |
 | [Day 37](./day37) | [Radix Sort](./day37) | [http://codetoexpress.tech/dc/day37/](http://codetoexpress.tech/dc/day37/) | **Misc** |
 | [Day 38](./day38) | [Implement Stack Data Structure](./day38) | [http://codetoexpress.tech/dc/day38/](http://codetoexpress.tech/dc/day38/) | **Beginner** |
+| [Day 39](./day39) | [Maximum Element and Reverse Stack](./day39) | [http://codetoexpress.tech/dc/day39/](http://codetoexpress.tech/dc/day39/) | **Intermediate** |
 
 ## [More Problems](./BONUS/README.md)
 

day39/Daily Codes.png

@@ -0,0 +1,69 @@
+/**
+ * Find maximum element in the stack
+ * @author MadhavBahlMD
+ * @date 12/02/2019
+ */
+
+class Stack {
+    constructor (limit) {
+        this.myStack = [];
+        this.tempStack = [];
+        this.capacity = limit;
+    }
+
+    // Implement isFull() method
+    isFull () {
+        if (this.myStack.length === this.capacity)  return true;
+        return false;
+    }
+
+    // Implement isEmpty() method
+    isEmpty () {
+        if (this.myStack.length === 0)  return true;
+        return false;
+    }
+
+    // Implement push(x) method
+    push (element) {
+        if (this.isFull()) return false;
+        this.myStack.push(element);
+        return true;
+    }
+
+    // Implement pop() method
+    pop () {
+        if (this.isEmpty())  return -1;
+        return this.myStack.pop();
+    }
+
+    // Implement the peek() function 
+    peek () {
+        return this.myStack[this.myStack.length - 1];
+    }
+
+    // Implement findMax() method
+    findMax () {
+        this.tempStack = this.myStack;
+        let max = this.peek();
+
+        while (!this.isEmpty()) {
+            let currentTop = this.pop();
+            if (currentTop > max) max = currentTop;
+        }
+
+        this.myStack = this.tempStack;
+        return max;
+    }
+}
+
+const stk = new Stack (10);
+stk.push (1);
+stk.push (2);
+stk.push (19);
+stk.push (12);
+stk.push (16);
+stk.push (4);
+stk.push (25);
+stk.push (5);
+
+console.log (stk.findMax());

day39/JavaScript/maxElement.js

@@ -0,0 +1,81 @@
+/**
+ * Reverse the stack
+ * @author MadhavBahlMD
+ * @date 12/02/2019
+ */
+
+class Stack {
+    constructor (limit) {
+        this.myStack = [];
+        this.tempStack = [];
+        this.capacity = limit;
+    }
+
+    // Implement isFull() method
+    isFull () {
+        if (this.myStack.length === this.capacity)  return true;
+        return false;
+    }
+
+    // Implement isEmpty() method
+    isEmpty () {
+        if (this.myStack.length === 0)  return true;
+        return false;
+    }
+
+    // Implement push(x) method
+    push (element) {
+        if (this.isFull()) return false;
+        this.myStack.push(element);
+        return true;
+    }
+
+    // Implement pop() method
+    pop () {
+        if (this.isEmpty())  return -1;
+        return this.myStack.pop();
+    }
+
+    // Implement the peek() function 
+    peek () {
+        return this.myStack[this.myStack.length - 1];
+    }
+
+    // Implement reverse() method
+    reverse () {
+        this.tempStack = [];
+        while (!this.isEmpty()) {
+            let top = this.pop ();
+            console.log ('temp = ', top);
+            this.tempStack.push (top);
+        }
+        this.myStack = this.tempStack;
+    }
+
+    // Implement displayAll() method
+    displayAll () {
+        console.log ('/* ==== My Stack ==== */');
+        console.log ('Top');
+
+        this.tempStack = this.myStack;
+        while (!this.isEmpty())
+            console.log (this.pop());
+        this.myStack = this.tempStack;
+
+        console.log ('Bottom');
+    }
+}
+
+const stk = new Stack (10);
+stk.push (1);
+stk.push (2);
+stk.push (19);
+stk.push (12);
+stk.push (16);
+stk.push (4);
+stk.push (25);
+stk.push (5);
+
+stk.displayAll ();
+stk.reverse ();
+stk.displayAll ();

day39/JavaScript/stackReverse.js

@@ -0,0 +1,180 @@
+![cover](./cover.png)
+
+# Day 39 - Maximum Element and Stack Reversal
+
+## Question 1 
+
+Find the maximum element in the stack
+
+## Question 2
+
+Reverse the given stack
+
+**HINT**
+
+- You can use another stack, pop the elements of first stack and push them onto the second stack
+- You can reverse without another data structure using recursion
+
+## Solution to Question 1
+
+### [JavaScript Implementation](./JavaScript/maxElement.js)
+
+```js
+/**
+ * Find maximum element in the stack
+ * @author MadhavBahlMD
+ * @date 12/02/2019
+ */
+
+class Stack {
+    constructor (limit) {
+        this.myStack = [];
+        this.tempStack = [];
+        this.capacity = limit;
+    }
+
+    // Implement isFull() method
+    isFull () {
+        if (this.myStack.length === this.capacity)  return true;
+        return false;
+    }
+
+    // Implement isEmpty() method
+    isEmpty () {
+        if (this.myStack.length === 0)  return true;
+        return false;
+    }
+
+    // Implement push(x) method
+    push (element) {
+        if (this.isFull()) return false;
+        this.myStack.push(element);
+        return true;
+    }
+
+    // Implement pop() method
+    pop () {
+        if (this.isEmpty())  return -1;
+        return this.myStack.pop();
+    }
+
+    // Implement the peek() function 
+    peek () {
+        return this.myStack[this.myStack.length - 1];
+    }
+
+    // Implement findMax() method
+    findMax () {
+        this.tempStack = this.myStack;
+        let max = this.peek();
+
+        while (!this.isEmpty()) {
+            let currentTop = this.pop();
+            if (currentTop > max) max = currentTop;
+        }
+
+        this.myStack = this.tempStack;
+        return max;
+    }
+}
+
+const stk = new Stack (10);
+stk.push (1);
+stk.push (2);
+stk.push (19);
+stk.push (12);
+stk.push (16);
+stk.push (4);
+stk.push (25);
+stk.push (5);
+
+console.log (stk.findMax());
+```
+
+## Solution to Question 2
+
+### [JavaScript Implementation](./JavaScript/stackReverse.js)
+
+```js
+/**
+ * Reverse the stack
+ * @author MadhavBahlMD
+ * @date 12/02/2019
+ */
+
+class Stack {
+    constructor (limit) {
+        this.myStack = [];
+        this.tempStack = [];
+        this.capacity = limit;
+    }
+
+    // Implement isFull() method
+    isFull () {
+        if (this.myStack.length === this.capacity)  return true;
+        return false;
+    }
+
+    // Implement isEmpty() method
+    isEmpty () {
+        if (this.myStack.length === 0)  return true;
+        return false;
+    }
+
+    // Implement push(x) method
+    push (element) {
+        if (this.isFull()) return false;
+        this.myStack.push(element);
+        return true;
+    }
+
+    // Implement pop() method
+    pop () {
+        if (this.isEmpty())  return -1;
+        return this.myStack.pop();
+    }
+
+    // Implement the peek() function 
+    peek () {
+        return this.myStack[this.myStack.length - 1];
+    }
+
+    // Implement reverse() method
+    reverse () {
+        this.tempStack = [];
+        while (!this.isEmpty()) {
+            let top = this.pop ();
+            console.log ('temp = ', top);
+            this.tempStack.push (top);
+        }
+        this.myStack = this.tempStack;
+    }
+
+    // Implement displayAll() method
+    displayAll () {
+        console.log ('/* ==== My Stack ==== */');
+        console.log ('Top');
+
+        this.tempStack = this.myStack;
+        while (!this.isEmpty())
+            console.log (this.pop());
+        this.myStack = this.tempStack;
+
+        console.log ('Bottom');
+    }
+}
+
+const stk = new Stack (10);
+stk.push (1);
+stk.push (2);
+stk.push (19);
+stk.push (12);
+stk.push (16);
+stk.push (4);
+stk.push (25);
+stk.push (5);
+
+stk.displayAll ();
+stk.reverse ();
+stk.displayAll ();
+```