EASY NC#50 Blind #61 Trees
100. Same Tree
📖 Problem
Given the roots of two binary trees p and q, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical, and the nodes have the same value.
🧠 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
- •Level-order traversal
- •Queue discipline
- •Shortest-step interpretation
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
- •Apply BFS reasoning pattern
- •Apply Recursion reasoning pattern
💡 Approach
- → Use recursive approach to compare corresponding nodes
- → Base case: both null (same), one null (different)
- → Compare values and recursively check both subtrees
- → Time: O(min(m, n)), Space: O(h) where h is tree height
🛠️ Hints & Pitfalls
Hints
- •Use recursive approach to compare corresponding nodes
- •Base case: both null (same), one null (different)
- •Compare values and recursively check both subtrees
Common Pitfalls
- •Time: O(min(m, n)), Space: O(h) where h is tree height
🧪 Test Cases
Hidden tests on submit: 3
Test Case 1
Not run Input:
buildTree([1,2,3]); Expected:
{"val":1,"left":{"val":2,"left":null,"right":null},"right":{"val":3,"left":null,"right":null}} Test Case 2
Not run Input:
buildTree([1,2]); Expected:
{"val":1,"left":{"val":2,"left":null,"right":null},"right":null} Test Case 3
Not run Input:
buildTree([1,null,2]); Expected:
{"val":1,"left":null,"right":{"val":2,"left":null,"right":null}} 📝 Code Editor
📤 Output