g0501_0600.s0563_binary_tree_tilt.Solution.kt Maven / Gradle / Ivy

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package g0501_0600.s0563_binary_tree_tilt

// #Easy #Depth_First_Search #Tree #Binary_Tree
// #2023_01_21_Time_197_ms_(100.00%)_Space_35.8_MB_(75.00%)

import com_github_leetcode.TreeNode

/*
 * Example:
 * var ti = TreeNode(5)
 * var v = ti.`val`
 * Definition for a binary tree node.
 * class TreeNode(var `val`: Int) {
 *     var left: TreeNode? = null
 *     var right: TreeNode? = null
 * }
 */
class Solution {
    private var sum = 0
    private fun sumTilt(root: TreeNode?): Int {
        if (root == null) {
            return 0
        }
        val ls = sumTilt(root.left)
        val rs = sumTilt(root.right)
        sum += Math.abs(ls - rs)
        return ls + rs + root.`val`
    }

    fun findTilt(root: TreeNode?): Int {
        sum = 0
        sumTilt(root)
        return sum
    }
}