Serialize and Deserialize Binary Tree (LC #297) tests your design skills. Meta notes this is critical for storing hierarchical data like Facebook Groups. For serialization, use preorder traversal with null markers. Separate values with commas. For deserialization, split by comma, use a queue, and rebuild recursively: take the next value, if null return null, else create node and recurse for left and right. Both operations run in time and space. Meta cares about your format choices and null handling.
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$ curl repovive.com/roadmaps/meta-interview-prep/trees/serialize-and-deserialize-binary-tree
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