Binary Tree Tilt

Input: root = [1,2,3]

Output: 1

Tilt of node 2: |0-0| = 0 (no children). Tilt of node 3: |0-0| = 0 (no children). Tilt of node 1: |2-3| = 1 (left subtree sum is 2, right subtree sum is 3). Total tilt: 0 + 0 + 1 = 1.

Input: root = [4,2,9,3,5,null,7]

Output: 15

Tilt of leaves (3, 5, 7): 0 each. Tilt of node 2: |3-5| = 2. Tilt of node 9: |0-7| = 7. Tilt of node 4: |10-16| = 6. Total: 0 + 0 + 0 + 2 + 7 + 6 = 15.

Input: root = [21,7,14,1,1,2,2,3,3]

Output: 9

Sum the absolute differences between left and right subtree sums for each node.

Problem

Constraints

Examples