Leetcode/1026

README.md

@@ -220,6 +220,7 @@
 - [1089: Duplicate Zeros](problems/leetcode/1089) - Queue
 - [1198: Find smallest common element in all rows](problems/leetcode/1198) - Matrix
 - [1208: Unique number of occurrences](problems/leetcode/1208) - Set + Map
+- [1026: Maximum difference between node and ancestor](problems/leetcode/1026) - Medium - Tree
 - [1235: Maximum profit in job scheduling](problems/leetcode/1235) - Dynamic Programming + Binary Search
 - [1239: Maximum length of a concatenated string with unique characters](problems/leetcode/1239)
 - [1323: Maximum 69 number](problems/leetcode/1323)

problems/leetcode/1026/solution.js

@@ -0,0 +1,46 @@
+/**
+ * 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}
+ */
+var maxAncestorDiff = function(root) {
+  let diff = 0;
+  let min = root.val;
+  let max = root.val;
+
+  if (!root) {
+      return diff;
+  }
+
+  dfs(root, min, max);
+
+  return diff;
+
+  function dfs(node, min, max) {
+      if (!node) {
+          return;
+      }
+
+      diff = Math.max(
+          diff,
+          Math.max(
+              Math.abs(min - node.val),
+              Math.abs(max - node.val)
+          )
+      );
+
+      min = Math.min(min, node.val);
+      max = Math.max(max, node.val);
+
+      dfs(node.left, min, max);
+      dfs(node.right, min, max);
+  }
+
+};