Below is a high-yield, pattern-driven set of stack problems. This covers all core concepts:
- LIFO behavior
- monotonic stacks
- parsing / evaluation
- recursion simulation
- next greater/smaller patterns
1. Basic Stack Usage (Validation)
Core Skill
- Push / pop matching elements
Problems
- Valid Parentheses
- Min Stack
Concepts
- Matching pairs
- Maintaining auxiliary state (min stack)
2. Monotonic Stack (CRITICAL)
Core Skill
- Maintain increasing or decreasing order