delete-leaves-with-a-given-value

< Previous 　　　　　　　　　　　　　　　　 Next >

1325. Delete Leaves With a Given Value (Medium)

Given a binary tree root and an integer target, delete all the leaf nodes with value target.

Note that once you delete a leaf node with value target, if it's parent node becomes a leaf node and has the value target, it should also be deleted (you need to continue doing that until you can't).

 

Example 1:

Input: root = [1,2,3,2,null,2,4], target = 2
Output: [1,null,3,null,4]
Explanation: Leaf nodes in green with value (target = 2) are removed (Picture in left). 
After removing, new nodes become leaf nodes with value (target = 2) (Picture in center).

Example 2:

Input: root = [1,3,3,3,2], target = 3
Output: [1,3,null,null,2]

Example 3:

Input: root = [1,2,null,2,null,2], target = 2
Output: [1]
Explanation: Leaf nodes in green with value (target = 2) are removed at each step.

Example 4:

Input: root = [1,1,1], target = 1
Output: []

Example 5:

Input: root = [1,2,3], target = 1
Output: [1,2,3]

 

Constraints:

• 1 <= target <= 1000
• Each tree has at most 3000 nodes.
• Each node's value is between [1, 1000].

Related Topics

[Tree]

Hints

Hint 1

Use the DFS to reconstruct the tree such that no leaf node is equal to the target. If the leaf node is equal to the target, return an empty object instead.