import java.util.ArrayList;
import java.util.List;
/**
* https://leetcode.com/articles/two-sum-iv/
*/
public class TwoSumIV {
public boolean findTarget(TreeNode root, int k) {
List nums = new ArrayList<>();
inorder(root, nums);
for (int i = 0, j = nums.size() - 1; i < j; ) {
if (nums.get(i) + nums.get(j) == k) return true;
if (nums.get(i) + nums.get(j) < k) i++;
else j--;
}
return false;
}
public void inorder(TreeNode root, List nums) {
if (root == null) return;
inorder(root.left, nums);
nums.add(root.val);
inorder(root.right, nums);
}
}