Overview
Stack LIFO (Last In First Out) structure hai jisme push, pop, peek operations hain.
Analogy
Jaise thali stack karna—jo thali last rakhi woh pehle uthayenge.
Step-by-step
- push element stack ke top par add karta hai
- pop top element delete karke return karta hai
- peek top dekhta hai lekin delete nahi karta
- is_empty check karta hai khaali hai ya nahi
Visual
stack = []
stack.append(1) # push
stack.append(2)
stack.pop() # → 2
stack[-1] # peek → 1
Common mistakes
- Khaali stack par pop karna IndexError deta hai
- Queue operations use karna
- Peek pop nahi hai—delete nahi karta
Practice questions
- Stack se string reverse karo
- Stack se infix expression postfix mein convert karo