4.4---建立二叉树的链表

public class TreeLevel {
public ListNode getTreeLevel(TreeNode root, int dep) {
// write code here
List<TreeNode> result = new ArrayList();
ListNode res = null;
if(root == null || dep <= 0    ){
return res;
}
result.add(root);
if(dep == 1){
res = new ListNode(root.val);
return res;
}

while(dep > 1){
List<TreeNode> temp = new ArrayList();
for(TreeNode t : result){
if(t.left != null) temp.add(t.left);
if(t.right != null) temp.add(t.right);
}
result = temp;
dep--;
}

res = new ListNode(result.get(0).val);
ListNode temp = res;
for(int i = 1; i < result.size(); i++){
temp.next = new ListNode(result.get(i).val);
temp = temp.next;
}
return res;
}
}