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Grokking the Coding Interview Patterns in C++

Solution: Binary Tree Cameras

Explore a dynamic programming approach to determine the minimum cameras needed to cover all nodes of a binary tree. Understand how to evaluate node states and apply post-order traversal to optimize camera placement efficiently. This lesson helps you implement and analyze a recursive solution that balances coverage and camera count.

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Statement

You are given the root of a binary tree. Cameras can be installed on any node, and each camera can monitor itself, its parent, and its immediate children.

Your task is to determine the minimum number of cameras required to monitor every node in the tree.

Constraints:

  • The number of nodes in the tree is in the range [1,1000][1, 1000].

  • Node.data ==0== 0

Solution

Each node in the tree can be in one of three possible states, based on how it's monitored:

  • State 0 (Not covered): All the nodes below this ...