Day 318: Binary Tree Maximum Path Sum | Clean DFS + Recursion Explanation

Day 318 of my #300DaysOfCode! Today I solved one of the most classic LeetCode Hard tree problems: Binary Tree Maximum Path Sum. This problem confuses many because the “maximum path” does not have to start at the root — it can pass through any node. The key idea is using DFS + postorder recursion and returning the best “single-side gain” from each subtree while updating the global maximum. In this video, I explain: Why the max path may pass THROUGH a node What “single-path gain” and “through-path gain” mean Why we return max(left, right, 0) + node.val How the global res gets updated inside DFS Full dry-run of DFS transitions Clean and simple recursive implementation Master this problem and all tree DP/DFS problems become 10× easier. 📌 Full code walkthrough included 📌 Beginner-friendly explanation 📌 Perfect for interviews & LeetCode Hard practice 👉 Comment the next tree problem I should solve on Day 319! 👉 Subscribe for daily Java/DSA videos! #365daysofcode #leetcode #leetcodehard #binarytree #dfs #dsa #treeproblems #recursion #python #codingjourney #beginnerprogrammer