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Amount of Time for Binary Tree to Be Infected (medium)
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Problem Statement

You are given the root of a binary tree with unique values and an integer start.

At the start time (minute 0), an infection starts from the node with the value start.

Each minute, a node becomes infected if:

  • It is currently uninfected.
  • It is adjacent to an infected node.

Return the number of minutes required for the entire tree to become infected.

Examples

Example 1:

  • Input: root = [1, 2, 3, null, 4, 5, 6], start = 3
  • Expected Output: 3
  • Explanation: The tree structure is: 
        1
   / \
  2   3

.....

.....

.....

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