Binary Tree Tilt

// 563. Binary Tree Tilt // // https://leetcode.com/problems/binary-tree-tilt/ // Definition for a binary tree node. // type TreeNode struct { // Val int // Left *TreeNode // Right *TreeNode // } // search function search the absolute difference on global variable result. // Each node find the difference of the left and right child, and add to the result. // To record the difference correctly, every value of the left and right child should be return to the upward. // When the recursive call of this function to the end, every tilt value can be accumulated. func search(root *TreeNode, result *int) int { if root == nil { return 0 } left, right := search(root.Left, result), search(root.Right, result) diff := left - right if diff < 0 { diff *= -1 } *result += diff return left + right + root.Val } func findTilt(root *TreeNode) int { result := 0 _ = search(root, &result) return result }