Topic 7 Stack
🧑💻 Introduction to Stack
A stack is a linear data structure that follows the Last In, First Out (LIFO) principle. Think of it like a stack of plates 🍽️ — you always add new plates on top and take the top one off first.
Stacks are powerful tools used to solve a variety of problems efficiently. They’re like a magic box 🧙♂️ for handling nested structures, evaluating expressions, and keeping track of previous elements in many algorithms.
⚡ Key Operations of a Stack
Push: Add an element to the top of the stack 🆙
Pop: Remove the top element from the stack 🔽
Peek or Top: Look at the top element without removing it 👀
IsEmpty: Check if the stack is empty 🚫
Size: Get the number of elements in the stack 📏
💡 Where are Stacks Used?
Stacks are commonly used in scenarios like:
Expression evaluation (e.g., arithmetic expressions, reverse Polish notation) ➗
Parsing and backtracking (e.g., balanced parentheses) 🧩
Depth-first search (DFS) in graph traversal 🌲
They can be implemented using arrays or linked lists, and many algorithms rely on stack-based operations to solve problems effectively.
📝 Problems in the Stack Topic
Valid Parentheses Problem URL: LeetCode - Valid Parentheses Study here 📘
Simplify Path Problem URL: LeetCode - Simplify Path Study here 📘
Min Stack Problem URL: LeetCode - Min Stack Study here 📘
Evaluate Reverse Polish Notation Problem URL: LeetCode - Evaluate Reverse Polish Notation Study here 📘
Basic Calculator Problem URL: LeetCode - Basic Calculator Study here 📘
🎉 Conclusion
Congrats on diving into stacks! 🎊 Stacks are a fundamental data structure that can help you solve problems efficiently in various scenarios, like evaluating expressions, navigating through nested structures, and backtracking. 🚀
Take your time exploring each problem and its solution. You'll see how stacks can make even the trickiest problems simpler and more manageable! 😊
✨ Happy coding! 💻✨
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