• Home
• com.github.javadev
• leetcode-in-java
• 1.23
• source code
• readme.md

×

Project download

Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $

You can buy this project and download/modify it how often you want.

g0901_1000.s0968_binary_tree_cameras.readme.md Maven / Gradle / Ivy

968\. Binary Tree Cameras

Hard

You are given the `root` of a binary tree. We install cameras on the tree nodes where each camera at a node can monitor its parent, itself, and its immediate children.

Return _the minimum number of cameras needed to monitor all nodes of the tree_.

**Example 1:**

![](https://assets.leetcode.com/uploads/2018/12/29/bst_cameras_01.png)

**Input:** root = [0,0,null,0,0]

**Output:** 1

**Explanation:** One camera is enough to monitor all nodes if placed as shown.

**Example 2:**

![](https://assets.leetcode.com/uploads/2018/12/29/bst_cameras_02.png)

**Input:** root = [0,0,null,0,null,0,null,null,0]

**Output:** 2

**Explanation:** At least two cameras are needed to monitor all nodes of the tree. The above image shows one of the valid configurations of camera placement.

**Constraints:**

*   The number of nodes in the tree is in the range `[1, 1000]`.
*   `Node.val == 0`