Add solution #515

Author: JoshCrozier

README.md

@@ -411,6 +411,7 @@
 509|[Fibonacci Number](./0509-fibonacci-number.js)|Easy|
 513|[Find Bottom Left Tree Value](./0513-find-bottom-left-tree-value.js)|Medium|
 514|[Freedom Trail](./0514-freedom-trail.js)|Hard|
+515|[Find Largest Value in Each Tree Row](./0515-find-largest-value-in-each-tree-row.js)|Medium|
 520|[Detect Capital](./0520-detect-capital.js)|Easy|
 521|[Longest Uncommon Subsequence I](./0521-longest-uncommon-subsequence-i.js)|Easy|
 530|[Minimum Absolute Difference in BST](./0530-minimum-absolute-difference-in-bst.js)|Easy|

solutions/0515-find-largest-value-in-each-tree-row.js

@@ -0,0 +1,40 @@
+/**
+ * 515. Find Largest Value in Each Tree Row
+ * https://leetcode.com/problems/find-largest-value-in-each-tree-row/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return an array of the largest value in each row
+ * of the tree (0-indexed).
+ */
+
+/**
+ * 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 largestValues = function(root) {
+  if (!root) return [];
+  const result = [];
+  const queue = [root];
+
+  while (queue.length) {
+    const level = queue.length;
+    let max = -Infinity;
+    for (let i = 0; i < level; i++) {
+      const node = queue.shift();
+      max = Math.max(max, node.val);
+      if (node.left) queue.push(node.left);
+      if (node.right) queue.push(node.right);
+    }
+    result.push(max);
+  }
+
+  return result;
+};