# Leetcode 563 - Binary tree tilt

`Note:`

`DFS`

all the way! I hate iterative traverses.- Base case: we are looking for
`num`

, so apparently when`node`

is null, we should return`0`

. - Return
`|leftSum - rightSum|`

.

`Question:`

Given the root of a binary tree, return the sum of every tree node’s tilt.

The tilt of a tree node is the absolute difference between the sum of all left subtree node values and all right subtree node values. If a node does not have a left child, then the sum of the left subtree node values is treated as 0. The rule is similar if there the node does not have a right child.

`Example:`

1 | Input: root = [1,2,3] |

`Code:`

1 | /** |