stacks and queues

Author: kunal-kushwaha

Diff for: lectures/19-stacks-n-queues/Stacks and Queues.pdf

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

Diff for: lectures/19-stacks-n-queues/code/.idea/.gitignore

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+package com.kunal;
+
+public class CircularQueue {
+    protected int[] data;
+    private static final int DEFAULT_SIZE = 10;
+
+    protected int end = 0;
+    protected int front = 0;
+    private int size = 0;
+
+    public CircularQueue(){
+        this(DEFAULT_SIZE);
+    }
+
+    public CircularQueue(int size) {
+        this.data = new int[size];
+    }
+
+    public boolean isFull() {
+        return size == data.length; // ptr is at last index
+    }
+
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    public boolean insert(int item) {
+        if (isFull()) {
+            return false;
+        }
+        data[end++] = item;
+        end = end % data.length;
+        size++;
+        return true;
+    }
+
+    public int remove() throws Exception {
+        if (isEmpty()) {
+            throw new Exception("Queue is empty");
+        }
+
+        int removed = data[front++];
+        front = front % data.length;
+        size--;
+        return removed;
+    }
+
+    public int front() throws Exception{
+        if (isEmpty()) {
+            throw new Exception("Queue is empty");
+        }
+        return data[front];
+    }
+
+    public void display() {
+        if (isEmpty()) {
+            System.out.println("Empty");
+            return;
+        }
+        int i = front;
+        do {
+            System.out.print(data[i] + " -> ");
+            i++;
+            i %= data.length;
+        } while (i != end);
+        System.out.println("END");
+    }
+
+}

Diff for: lectures/19-stacks-n-queues/code/.idea/description.html

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+package com.kunal;
+
+public class CustomQueue {
+    private int[] data;
+
+    private static final int DEFAULT_SIZE = 10;
+
+    int end = 0;
+
+    public CustomQueue(){
+        this(DEFAULT_SIZE);
+    }
+
+    public CustomQueue(int size) {
+        this.data = new int[size];
+    }
+
+    public boolean isFull() {
+        return end == data.length; // ptr is at last index
+    }
+
+    public boolean isEmpty() {
+        return end == 0;
+    }
+
+    public boolean insert(int item) {
+        if (isFull()) {
+            return false;
+        }
+        data[end++] = item;
+        return true;
+    }
+
+    public int remove() throws Exception {
+        if (isEmpty()) {
+            throw new Exception("Queue is empty");
+        }
+
+        int removed = data[0];
+
+        // shift the elements to left
+        for (int i = 1; i < end; i++) {
+            data[i-1] = data[i];
+        }
+        end--;
+        return removed;
+    }
+
+    public int front() throws Exception{
+        if (isEmpty()) {
+            throw new Exception("Queue is empty");
+        }
+        return data[0];
+    }
+
+    public void display() {
+        for (int i = 0; i < end; i++) {
+            System.out.print(data[i] + " <- ");
+        }
+        System.out.println("END");
+    }
+
+}

Diff for: lectures/19-stacks-n-queues/code/.idea/encodings.xml

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+package com.kunal;
+
+public class CustomStack {
+    protected int[] data;
+    private static final int DEFAULT_SIZE = 10;
+
+    int ptr = -1;
+
+    public CustomStack(){
+        this(DEFAULT_SIZE);
+    }
+
+    public CustomStack(int size) {
+        this.data = new int[size];
+    }
+
+    public boolean push(int item) {
+        if (isFull()) {
+            System.out.println("Stack is full!!");
+            return false;
+        }
+        ptr++;
+        data[ptr] = item;
+        return true;
+    }
+
+    public int pop() throws StackException {
+        if (isEmpty()) {
+            throw new StackException("Cannot pop from an empty stack!!");
+        }
+//        int removed = data[ptr];
+//        ptr--;
+//        return removed;
+        return data[ptr--];
+    }
+
+    public int peek() throws StackException {
+        if (isEmpty()) {
+            throw new StackException("Cannot peek from an empty stack!!");
+        }
+        return data[ptr];
+    }
+
+    public boolean isFull() {
+        return ptr == data.length - 1; // ptr is at last index
+    }
+
+    public boolean isEmpty() {
+        return ptr == -1;
+    }
+}