https://jeanphilogong.github.io/jeanblog/tags/binary-tree/Recent content in Binary Tree on Jeanphilo BlogHugo -- 0.168.0en-usMon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/124-binary-tree-maximum-path-sum/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/124-binary-tree-maximum-path-sum/A practical guide to LeetCode 124 covering the key design split: return only the best single-side gain upward, while using the full path through the current node to update a global answer.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/199-binary-tree-right-side-view/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/199-binary-tree-right-side-view/A practical guide to LeetCode 199 covering why the right side view is just the last node of each level, plus two stable solutions: level-order BFS and right-first DFS.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/105-construct-binary-tree-from-preorder-and-inorder-traversal/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/105-construct-binary-tree-from-preorder-and-inorder-traversal/A practical guide to LeetCode 105 covering how preorder chooses the root, how inorder splits the subtrees, and how a hash map plus index recursion reduces reconstruction to O(n).https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/108-convert-sorted-array-to-binary-search-tree/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/108-convert-sorted-array-to-binary-search-tree/A practical guide to LeetCode 108 covering why the midpoint is the natural root, how sorted order and balance requirements work together, and how to build the BST with stable index recursion.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/114-flatten-binary-tree-to-linked-list/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/114-flatten-binary-tree-to-linked-list/A practical guide to LeetCode 114 covering why the flattened list must follow preorder order and how reverse preorder with a prev pointer gives a stable in-place rewiring strategy.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/230-kth-smallest-element-in-a-bst/Mon, 20 Apr 2026 10:01:46 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/230-kth-smallest-element-in-a-bst/A practical guide to LeetCode 230 covering why inorder traversal of a BST is sorted, how to count visits with an explicit stack, and how to stop immediately at the k-th node.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/543-diameter-of-binary-tree/Sun, 19 Apr 2026 15:51:55 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/543-diameter-of-binary-tree/A practical guide to LeetCode 543 covering the key split between returned height and global diameter updates, plus engineering mappings and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/236-lowest-common-ancestor-of-a-binary-tree/Sun, 19 Apr 2026 15:51:55 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/236-lowest-common-ancestor-of-a-binary-tree/A practical guide to LeetCode 236 covering the return-value meaning in postorder recursion, when the current node becomes the answer, and why a node can be its own ancestor.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/98-validate-binary-search-tree/Sun, 19 Apr 2026 15:13:19 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/98-validate-binary-search-tree/A practical guide to LeetCode 98 covering ancestor range constraints, why parent-only checks fail, and two stable solutions: recursive bounds and inorder validation.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/102-binary-tree-level-order-traversal/Mon, 16 Mar 2026 13:00:56 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/102-binary-tree-level-order-traversal/A practical guide to LeetCode 102 covering level-by-level BFS, level-size boundaries, DFS depth buckets, and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/101-symmetric-tree/Mon, 16 Mar 2026 13:00:55 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/101-symmetric-tree/A practical guide to LeetCode 101 covering mirror recursion, pairwise BFS checks, symmetry contracts, and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/100-same-tree/Mon, 16 Mar 2026 13:00:54 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/100-same-tree/A practical guide to LeetCode 100 covering synchronous recursion, pairwise BFS validation, structural equivalence, and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/226-invert-binary-tree/Fri, 06 Mar 2026 17:58:23 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/226-invert-binary-tree/A practical guide to LeetCode 226 covering tree mirroring, recursive left-right swaps, BFS traversal, and engineering mappings.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/104-maximum-depth-of-binary-tree/Fri, 06 Mar 2026 17:58:22 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/104-maximum-depth-of-binary-tree/A practical guide to LeetCode 104 covering the depth definition, recursive DFS, level-order BFS, engineering mappings, and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/94-binary-tree-inorder-traversal/Fri, 06 Mar 2026 17:58:21 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/hot100/binary-tree/94-binary-tree-inorder-traversal/A practical guide to LeetCode 94 covering left-root-right traversal, recursion, explicit stacks, engineering mappings, and runnable multi-language implementations.https://jeanphilogong.github.io/jeanblog/alg/leetcode/437-path-sum-iii/Wed, 04 Feb 2026 16:02:26 +0800https://jeanphilogong.github.io/jeanblog/alg/leetcode/437-path-sum-iii/Count downward paths in a binary tree whose sum equals targetSum in O(n) using prefix sums and a frequency hash map, with derivation, engineering mapping, and multi-language implementations.