Find All the Lonely Nodes
给一个二叉树, 定一个lonely node是一个node只有一个child, 返回这些child. 用层序扫描即可.
/**
* 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 {
public List<Integer> getLonelyNodes(TreeNode root) {
Queue<TreeNode> q = new LinkedList<>();
q.add(root);
List<Integer> res = new ArrayList<>();
while(!q.isEmpty()) {
int size = q.size();
for(int i = 0; i < size; i++) {
TreeNode node = q.poll();
if(node.left != null && node.right == null)
{
res.add(node.left.val);
}
if(node.left == null && node.right != null)
{
res.add(node.right.val);
}
if(node.left != null) {
q.add(node.left);
}
if(node.right != null) {
q.add(node.right);
}
}
}
return res;
}
}