[ PS ] : Binary Tree Maximum Path Sum

Author: uraflower

binary-tree-maximum-path-sum/uraflower.js

@@ -0,0 +1,33 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+const maxPathSum = function (root) {
+    let max = root.val;
+
+    function getMaxSum(node) {
+        if (!node) return 0;
+
+        const leftVal = Math.max(getMaxSum(node.left), 0);
+        const rightVal = Math.max(getMaxSum(node.right), 0);
+
+        max = Math.max(node.val + leftVal + rightVal, max);
+
+        return node.val + Math.max(leftVal, rightVal);
+    }
+
+    getMaxSum(root);
+
+    return max;
+};
+
+// 시간복잡도: O(n)
+// 공간복잡도: O(h) (h: 트리의 높이, 즉 재귀 스택 깊이)