Java: Elements from two stacks without duplicates

Java Stack: Exercise-23 with Solution

Write a Java program that implements a stack and creates a new stack that contains all elements from two stacks without duplicates.

Sample Solution:

Java Code:

``````import java.util.Scanner;

public class Stack {
private int[] arr;
private int top;

// Constructor to initialize the stack
public Stack(int size) {
arr = new int[size];
top = -1;
}

// Method to push an element onto the stack
public void push(int num) {
if (top == arr.length - 1) {
System.out.println("Stack is full");
} else {
top++;
arr[top] = num;
}
}

// Method to pop an element from the stack
public int pop() {
if (top == -1) {
System.out.println("Stack Underflow");
return -1;
} else {
int poppedElement = arr[top];
top--;
return poppedElement;
}
}

// Method to get the top element of the stack
public int peek() {
if (top == -1) {
System.out.println("Stack is empty");
return -1;
} else {
return arr[top];
}
}

// Method to check if the stack is empty
public boolean isEmpty() {
}

// Method to get the size of the stack
public int getSize() {
}

public static Stack findUniqueElements(Stack stack1, Stack stack2) {
Stack resultStack = new Stack(stack1.arr.length + stack2.arr.length);

// Add all elements from stack1 to resultStack
for (int i = 0; i <= stack1.top; i++) {
int element = stack1.arr[i];
if (!resultStack.contains(element)) {
resultStack.push(element);
}
}

// Add all elements from stack2 to resultStack
for (int i = 0; i <= stack2.top; i++) {
int element = stack2.arr[i];
if (!resultStack.contains(element)) {
resultStack.push(element);
}
}

return resultStack;
}

// Helper method to check if a stack contains an element
private boolean contains(int element) {
for (int i = 0; i <= top; i++) {
if (arr[i] == element) {
return true;
}
}
return false;
}

// Method to display the elements of the stack
public void display() {
if (top == -1) {
System.out.println("Stack is empty!");
} else {
System.out.print("Stack elements: ");
for (int i = top; i >= 0; i--) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
}

public static void main(String[] args) {
Stack result = new Stack(5);
Stack stack1 = new Stack(5);
stack1.push(1);
stack1.push(2);
stack1.push(3);
System.out.println("\nStack-1");
stack1.display();
Stack stack2 = new Stack(5);
stack2.push(3);
stack2.push(5);
stack2.push(6);
System.out.println("\nStack-2");
stack2.display();
Stack stack3 = new Stack(5);
stack3.push(1);
stack3.push(2);
stack3.push(4);
System.out.println("\nStack-3");
stack3.display();
System.out.println("\nNew stack that contains all elements from two stacks (stack1, stack2) without duplicates:");
result = findUniqueElements(stack1, stack2);
result.display();
System.out.println("\nNew stack that contains all elements from two stacks (stack1, stack3) without duplicates:");
result = findUniqueElements(stack1, stack3);
result.display();
System.out.println("\nNew stack that contains all elements from two stacks (stack3, stack2) without duplicates:");
result = findUniqueElements(stack3, stack2);
result.display();
}
}
```
```

Sample Output:

```Stack-1
Stack elements: 3 2 1

Stack-2
Stack elements: 6 5 3

Stack-3
Stack elements: 4 2 1

New stack that contains all elements from two stacks (stack1, stack2) without duplicates:
Stack elements: 6 5 3 2 1

New stack that contains all elements from two stacks (stack1, stack3) without duplicates:
Stack elements: 4 3 2 1

New stack that contains all elements from two stacks (stack3, stack2) without duplicates:
Stack elements: 6 5 3 4 2 1
```

Flowchart:

Live Demo:

Java Code Editor:

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Java Stack Previous: Find common elements between two stacks.
Java Stack Exercises Next: New stack from a portion of the original stack.

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