12-Stack-using-Array.md

Stack using Array

Problem Link

Practice Problem

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Pattern

• Stack
• Array

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Approach

Use a simple dynamic array with a top index to simulate stack behavior.

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Time Complexity

O(1) per operation

Space Complexity

O(n)

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Java Solution

class ArrayStack {
    private int[] arr;
    private int top = -1;

    public ArrayStack(int capacity) {
        arr = new int[capacity];
    }

    public void push(int val) {
        arr[++top] = val;
    }

    public int pop() {
        return arr[top--];
    }

    public int peek() {
        return arr[top];
    }
}