House robber III

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode() {} * TreeNode(int val) { this.val = val; } * TreeNode(int val, TreeNode left, TreeNode right) { * this.val = val; * this.left = left; * this.right = right; * } * } */ class Solution { /* cases for the any give node //consider if root.val is considered then we can explore root.left.left , root.left.right , root.right.left and root.right.right //not consider if root.val is not considered the we can explore root.left and root.right return Integer.max(consider, not consider) */ public int rob(TreeNode root) { Map<TreeNode,Integer> dp = new HashMap<>(); return max(root,dp); } public int max(TreeNode root,Map<TreeNode,Integer> dp){ if(root ==null )return 0; if(dp.containsKey(root)) return dp.get(root); int considerRoot = root.val; if(root.left!=null){ considerRoot+=max(root.left.left,dp) + max(root.left.right,dp); } if(root.right!=null){ considerRoot+=max(root.right.left,dp) + max(root.right.right,dp); } int dontConsiderRoot = max(root.left,dp) + max(root.right,dp); dp.put(root,Integer.max(considerRoot,dontConsiderRoot)); return dp.get(root) ; } }