Find Largest Value in Each Tree Row

Author: lessfish

Algorithms/Find Largest Value in Each Tree Row/find-largest-value-in-each-tree-row.js

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+// Source : https://leetcode.com/problems/find-largest-value-in-each-tree-row/
+// Author : Han Zichi
+// Date   : 2016-02-17
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+var largestValues = function(root) {
+  let maxn = [];
+
+  let dfs = (node, step) => {
+    if (!node) return;
+    if (maxn[step] === void 0)
+      maxn[step] = node.val;
+    else
+      maxn[step] = Math.max(node.val, maxn[step]);
+    dfs(node.left, step + 1);
+    dfs(node.right, step + 1);
+  };
+
+  dfs(root, 0);
+  return maxn;
+};