leetcode 337

house_robber_III.kt

/**
 * 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 {
    fun rob(root: TreeNode?): Int {
        val ans = dfs(root)
        return Math.max(ans[0], ans[1])
    }
    
    fun dfs(node: TreeNode?): IntArray {
        return if(node == null) {
            IntArray(2) {0}
        } else {
            val left = dfs(node!!.left)
            val right = dfs(node!!.right)
            
            val result = IntArray(2)
            
            //>> select root
            result[0] = node!!.`val` + left[1] + right[1]
            
            //>> select child
            result[1] = Math.max(left[0], left[1]) + Math.max(right[0], right[1])
            
            return result
        }
    }
}