1273. Delete Tree Nodes

https://leetcode.com/problems/delete-tree-nodes

Description

A tree rooted at node 0 is given as follows:

• The number of nodes is nodes;

• The value of the i-th node is value[i];

• The parent of the i-th node is parent[i].

Remove every subtree whose sum of values of nodes is zero.

After doing so, return the number of nodes remaining in the tree.

Example 1:

**Input:** nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-1]
**Output:** 2

Example 2:

**Input:** nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-2]
**Output:** 6

Example 3:

**Input:** nodes = 5, parent = [-1,0,1,0,0], value = [-672,441,18,728,378]
**Output:** 5

Example 4:

**Input:** nodes = 5, parent = [-1,0,0,1,1], value = [-686,-842,616,-739,-746]
**Output:** 5

Constraints:

• 1 <= nodes <= 10^4

• parent.length == nodes

• 0 <= parent[i] <= nodes - 1

• parent[0] == -1 which indicates that 0 is the root.

• value.length == nodes

• -10^5 <= value[i] <= 10^5

• The given input is guaranteed to represent a valid tree.

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