[LeetCode Sync] Runtime - 5 ms (9.78%), Memory - 19.8 MB (6.38%)

Author: NamVr

0515-find-largest-value-in-each-tree-row/README.md

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+<p>Given the <code>root</code> of a binary tree, return <em>an array of the largest value in each row</em> of the tree <strong>(0-indexed)</strong>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<img alt="" src="https://assets.leetcode.com/uploads/2020/08/21/largest_e1.jpg" style="width: 300px; height: 172px;" />
+<pre>
+<strong>Input:</strong> root = [1,3,2,5,3,null,9]
+<strong>Output:</strong> [1,3,9]
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> root = [1,2,3]
+<strong>Output:</strong> [1,3]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li>The number of nodes in the tree will be in the range <code>[0, 10<sup>4</sup>]</code>.</li>
+	<li><code>-2<sup>31</sup> &lt;= Node.val &lt;= 2<sup>31</sup> - 1</code></li>
+</ul>

0515-find-largest-value-in-each-tree-row/solution.py

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+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def largestValues(self, root: Optional[TreeNode]) -> List[int]:
+        if not root:
+            return []
+
+        res = []
+        q = deque([root])
+
+        #BFS
+        while q:
+            m = float("-inf")
+
+            for _ in range(len(q)):
+                node = q.popleft()
+                m = max(m, node.val)
+
+                if (node.left):
+                    q.append(node.left)
+                if (node.right):
+                    q.append(node.right)
+            res.append(m)
+
+        return res