Binary Tree Cameras - Leetcode 968 ⚡Simple Greedy DFS | Python

Описание: Easiest Way to solve Binary Tree Cameras leetcode problem using a greedy postorder Depth First Search approach.
This is a classic binary tree interview problem where the goal is to place the minimum number of cameras so that every node in the tree is covered.
I have broken down the problem step by step, starting with why top-down approach does not work, followed by intuitive bottom-up examples and then uncover the key greedy insight: a camera is placed only when a child is uncovered. This leads naturally to a clean three-state model and an elegant postorder traversal solution. Also the I have discussed the edge case in detail for clarity.

This problem is frequently asked in FAANG interviews and is a must-know pattern for greedy tree problems and binary tree DFS questions.

Whether you’re preparing for coding interviews or mastering LeetCode tree problems, this video will help you understand not just how the solution works—but why it’s optimal.
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Leetcode 968. Binary Tree Cameras
🔗 Problem Link: https://leetcode.com/problems/binary-...
✅ Solution Page Link: https://dkodetree.com/solutions/binar...
💻 GitHub Solution Link: https://github.com/dkodetree/leetcode...

📌 Timestamps
00:00 - Problem Overview
01:18 - Why Preorder Fails?
03:03 - Why Bottom-Up (Postorder) DFS is Optimal?
04:30 - Greedy Rule for Minimum Number of Cameras
04:50 - Three Node States
06:00 - Root Edge Case
06:39 - Decision Table to Assign Node States
10:28 - Time and Space Complexity Explained
10:45 - Code in Python

📌 Quick Links:
🔹 Trees in Data Structures -    • 10. Trees - LeetCode Solutions  
🔹 DKodeTree Roots 25 – 🌱 Foundation Problems:
https://dkodetree.com/practice/dkodet...
🔹 Practice Series Solutions:
https://dkodetree.com/practice/series...
🔹 All my LeetCode Solutions:    • Total Leetcode Solutions on DKodeTree  
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