#2385
Amount of Time for Binary Tree to Be Infected
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hash table · tree · depth-first search · breadth-first search · binary tree
Description
You are given the root of a binary tree with unique values, and an integer start. At minute 0, an infection starts from the node with value start.
Each minute, a node becomes infected if:
- The node is currently uninfected.
- The node is adjacent to an infected node.
Return the number of minutes needed for the entire tree to be infected.
Example 1:
Input: root = [1,5,3,null,4,10,6,9,2], start = 3
Output: 4
Explanation: The following nodes are infected during:
- Minute 0: Node 3
- Minute 1: Nodes 1, 10 and 6
- Minute 2: Node 5
- Minute 3: Node 4
- Minute 4: Nodes 9 and 2
It takes 4 minutes for the whole tree to be infected so we return 4.
Example 2:
Input: root = [1], start = 1
Output: 0
Explanation: At minute 0, the only node in the tree is infected so we return 0.
Solution