HARD NC#121 Dynamic Programming
10. Regular Expression Matching
📖 Problem
Given an input string s and a pattern p, implement regular expression matching with support for '.' and ''. The matching should cover the entire input string (not partial).
🧠 Visual Learning Aid
1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases
JS/TS Refreshers
- •Array methods (`push`, `pop`, `shift`, `slice`)
- •Object/Map/Set usage patterns
- •Function parameter and return typing
- •Array DP table updates
- •State transition thinking
- •Base case initialization
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
- •Apply Dynamic Programming reasoning pattern
💡 Approach
- → Use dp[i][j] = does s[0:i] match p[0:j+1]
- → Handle '.' (matches any char) and '*' (matches 0 or more of preceding)
- → Time: O(m * n), Space: O(m * n)
🧭 Prerequisites
🛠️ Hints & Pitfalls
Hints
- •Use dp[i][j] = does s[0:i] match p[0:j+1]
- •Handle '.' (matches any char) and '*' (matches 0 or more of preceding)
- •Time: O(m * n), Space: O(m * n)
🧪 Test Cases
Hidden tests on submit: 1
Test Case 1
Not run Input:
isMatch('aa', 'a'); Expected:
false Test Case 2
Not run Input:
isMatch('aa', 'a*'); Expected:
false Test Case 3
Not run Input:
isMatch('ab', '.*'); Expected:
false 📝 Code Editor
📤 Output