/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
private int dfs(Set<Integer> subTreeSum, TreeNode root) {
if (root == null) return 0;
if (root.left == null && root.right == null) {
subTreeSum.add(root.val);
return root.val;
}
int left = dfs(subTreeSum, root.left);
subTreeSum.add(left);
int right = dfs(subTreeSum, root.right);
subTreeSum.add(right);
return left + right + root.val;
}
public boolean checkEqualTree(TreeNode root) {
if (root == null || (root.left == null && root.right == null)) return false;
Set<Integer> subTreeSum = new HashSet<>();
int total = dfs(subTreeSum, root);
if (total % 2 != 0) return false;
return subTreeSum.contains(total/2);
}
}