2641. Cousins in Binary Tree II

Medium

311

3

Given the `root`

of a binary tree, replace the value of each node in the tree with the **sum of all its cousins' values**.

Two nodes of a binary tree are **cousins** if they have the same depth with different parents.

Return *the *`root`

* of the modified tree*.

**Note** that the depth of a node is the number of edges in the path from the root node to it.

**Example 1:**

Input:root = [5,4,9,1,10,null,7]Output:[0,0,0,7,7,null,11]Explanation:The diagram above shows the initial binary tree and the binary tree after changing the value of each node. - Node with value 5 does not have any cousins so its sum is 0. - Node with value 4 does not have any cousins so its sum is 0. - Node with value 9 does not have any cousins so its sum is 0. - Node with value 1 has a cousin with value 7 so its sum is 7. - Node with value 10 has a cousin with value 7 so its sum is 7. - Node with value 7 has cousins with values 1 and 10 so its sum is 11.

**Example 2:**

Input:root = [3,1,2]Output:[0,0,0]Explanation:The diagram above shows the initial binary tree and the binary tree after changing the value of each node. - Node with value 3 does not have any cousins so its sum is 0. - Node with value 1 does not have any cousins so its sum is 0. - Node with value 2 does not have any cousins so its sum is 0.

**Constraints:**

- The number of nodes in the tree is in the range
`[1, 10`

.^{5}] `1 <= Node.val <= 10`

^{4}

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