* Definition for a binary tree node.
* public class TreeNode {
* TreeNode(int x) { val = x; }
public List<List<Integer>> verticalOrder(TreeNode root) {
List<List<Integer>> res = new ArrayList<>();
Queue<TreeNode> queue = new LinkedList<>();
Queue<Integer> distance = new LinkedList<>();
Map<Integer, List<Integer>> map = new HashMap<>();
while (!queue.isEmpty()) {
for (int i = 0; i < size; i++) {
TreeNode curNode = queue.remove();
int curDistance = distance.remove();
map.putIfAbsent(curDistance, new ArrayList<>());
map.get(curDistance).add(curNode.val);
if (curNode.left != null) {
distance.add(curDistance - 1);
min = Math.min(min, curDistance - 1);
if (curNode.right != null) {
queue.add(curNode.right);
distance.add(curDistance + 1);
max = Math.max(max, curDistance + 1);
for (int i = min; i <= max; i++) {