feat: maximum-depth-of-binary-tree

Author: minji-go

maximum-depth-of-binary-tree/minji-go.java

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+/**
+ * <a href="https://leetcode.com/problems/maximum-depth-of-binary-tree/">week4-2.maximum-depth-of-binary-tree</a>
+ * <li>Description: Given the root of a binary tree, return its maximum depth.</li>
+ * <li>Topics: Tree, Depth-First Search, Breadth-First Search, Binary Tree</li>
+ * <li>Time Complexity: O(N), Runtime 1ms</li>
+ * <li>Space Complexity: O(W), Memory 43.21MB</li>
+ */
+
+class Solution {
+    public int maxDepth(TreeNode root) {
+        if (root == null) return 0;
+
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.offer(root);
+
+        int depth = 0;
+        while (!queue.isEmpty()) {
+            depth++;
+            int size = queue.size();
+            for (int i = 0; i < size; i++) {
+                TreeNode node = queue.poll();
+                if (node.left != null) queue.offer(node.left);
+                if (node.right != null) queue.offer(node.right);
+            }
+        }
+        return depth;
+    }
+}