Grokking Tree Coding Patterns for Interviews
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Delete Leaves With a Given Value (medium)
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Problem Statement

Given a root node of a binary tree and an integer target, delete all leaf nodes that have a value equal to target.

After removing such leaf nodes, if any of their parent nodes become leaf nodes with a value equal to target, they should also be removed. This process should continue until no more nodes can be deleted.

Examples

Example 1

  • Input: root = [1, 5, 3, 5, null, 5, 4], Target: 5 here:
Image
  • Expected Output: [1,null,3,null,4]
  • Explanation: The left child of 5 (left of root) is 3 and 5. When we remove both leaf having value 5, the left node of the root also becomes a leaf having a value equal to 5. So, we also remove it.

Example 2

  • Input: root = [3, 3, 3, 3, 3, null, 4], Target: 3
Image
  • Expected Output: [3,null,3,null,4]
  • Explanation: Remove all 3 except the root and right child of the root node.

Example 3

  • Input: root = [4, 5, 6, 5, null, 7, 8], Target: 5
Image
  • Expected Output: [4,null,6,7,8]
  • Explanation: The leaf nodes with value 5 are removed first. The tree becomes [4, 5, 6, null, null, 7, 8]. Now, again remove the leaf node with the value 5 and the tree becomes [4, null, 6, 7, 8]`.

Constraints:

  • The number of nodes in the tree is in the range [1, 3000].
  • 1 <= Node.val, target <= 1000

Try it yourself

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Python3
Python3
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