按照之字形打印二叉树
描述
请实现一个函数按照之字形打印二叉树,即第一行按照从左到右的顺序打印,第二层按照从右至左的顺序打印,第三行按照从左到右的顺序打印,其他行以此类推。
Solution
public class Solution {
public ArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {
ArrayList<Integer> floor = new ArrayList<>();
int index=0;
Queue<TreeNode> queue = new LinkedList<>();
queue.offer(pRoot);
floor.add(1);
ArrayList<ArrayList<Integer>> arrayLists = new ArrayList<>();
while(!queue.isEmpty()){
floor.add(0);
ArrayList<Integer> arrayList = new ArrayList<>();
for(int i=0;i<floor.get(index);i++) {
TreeNode top = queue.poll();
if (top != null) {
arrayList.add(top.val);
queue.offer(top.left);
queue.offer(top.right);
floor.set(index+1,floor.get(index+1)+2);
}
}
if(arrayList.size()!=0){
if ((index & 1) == 1) Collections.reverse(arrayList);
arrayLists.add(arrayList);
}
index++;
}
return arrayLists;
}
}