Create MyStack.java

BaseMax · web-flow · commit 1b1afafb7519 · 2022-10-31T19:53:07.000+03:30
diff --git a/MyStack.java b/MyStack.java
@@ -0,0 +1,126 @@
+/*
+ * @Name: My Stack Implementation In Java
+ * @Author: Max Base
+ * @Date: 2022-10-31
+ * @Class: Data Structure, Dr. Mahsa Soheil Shamaee
+ */
+
+ // Stack
+class MyStack {
+    private int size;
+    private int top;
+    private int[] stack;
+
+    // Constructor
+    public MyStack(int size) {
+        this.size = size;
+        this.top = -1;
+        this.stack = new int[size];
+    }
+
+    // O(1)
+    // Push an element to the top of the stack and return true
+    // If the stack is full, throw an error and return false
+    public boolean push(int value) {
+        if (top == size - 1) {
+            System.out.println("Stack is full");
+            return false;
+        } else {
+            top++;
+            stack[top] = value;
+            return true;
+        }
+    }
+
+    // O(1)
+    // return -1 if stack is empty
+    // return top value if stack is not empty
+    // remove top value
+    public int pop() {
+        if (top == -1) {
+            System.out.println("Stack is empty");
+            return -1;
+        } else {
+            int value = stack[top];
+            top--;
+            return value;
+        }
+    }
+
+    // O(1)
+    // return -1 if stack is empty
+    // return top value if stack is not empty
+    // return top value without removing it
+    public int peek() {
+        if (top == -1) {
+            System.out.println("Stack is empty");
+            return -1;
+        } else {
+            return stack[top];
+        }
+    }
+
+    // O(1)
+    public boolean isEmpty() {
+        return top == -1;
+    }
+
+    // O(1)
+    public boolean isFull() {
+        return top == size - 1;
+    }
+
+    // O(1)
+    public int size() {
+        return top + 1;
+    }
+
+    public boolean resize(int newSize) {
+        if (newSize < size) {
+            System.out.println("New size is smaller than current size");
+            return false;
+        } else {
+            int[] newStack = new int[newSize];
+            for (int i = 0; i < size; i++) {
+                newStack[i] = stack[i];
+            }
+            stack = newStack;
+            size = newSize;
+            return true;
+        }
+    }
+
+    // O(n)
+    public void printStack() {
+        if (top == -1) {
+            System.out.println("Stack is empty");
+        } else {
+            System.out.println("Stack items:");
+            for (int i = top; i >= 0; i--) {
+                System.out.println(stack[i]);
+            }
+        }
+    }
+}
+
+// Example
+public class HelloWorld {
+    public static void main(String []args){
+        System.out.println("Hello, World!");
+
+        MyStack stack = new MyStack(5);
+        stack.push(1);
+        stack.push(2);
+        stack.push(3);
+        stack.push(4);
+        stack.push(5);
+
+        stack.printStack();
+
+        System.out.println("Peek: " + stack.peek());
+        System.out.println("Pop: " + stack.pop());
+        System.out.println("Peek: " + stack.peek());
+
+        stack.printStack();
+    }
+}
