# LeetCode Construct Binary Tree from Inorder and Postorder/Preorder Traversal: DFS

LeetCode Construct Binary Tree from Inorder and Postorder/Preorder Traversal: DFS, inorder determine the left/right subtree while pre/postorder determine the root.

# LeetCode Combinations: DFS vs Iterative

This LeetCode Combinations could be solved by using backtracking/DFS: C(n,k) = C(n-1, k-1) U n + C(n-1,k) and it could be done in iterative way too.

# LeetCode Climbing Stairs: DP vs Closed Form of Result

This LeetCode Climbing Stairs can be reduced to find the n-th number in Fibonacci Sequence, DP is the most common solution while closed form can be found too.

# LeetCode Binary Tree Zigzag Level Order Traversal: 2 Methods of BFS and DFS

LeetCode Binary Tree Zigzag Level Order Traversal could be again solved by both BFS and DFS with additional checking whether it is a zig level or zag level.

# LeetCode Binary Tree Level Order Traversal I and II: BFS and DFS

LeetCode Binary Tree Level Order Traversal I and II: Both BFS and DFS could be adopted to solve the problem, open question would be solve II without reversing.