二叉树最大宽度与leetcode662的二叉树最大宽度

public static int maxWidthUseMap(Node head) {
		if (head == null) {
			return 0;
		}
		Queue<Node> queue = new LinkedList<>();
		queue.add(head);
		// key 在 哪一层，value
		HashMap<Node, Integer> levelMap = new HashMap<>();
		levelMap.put(head, 1);
		int curLevel = 1; // 当前你正在统计哪一层的宽度
		int curLevelNodes = 0; // 当前层curLevel层，宽度目前是多少
		int max = 0;
		while (!queue.isEmpty()) {
			Node cur = queue.poll();
			int curNodeLevel = levelMap.get(cur);
			if (cur.left != null) {
				levelMap.put(cur.left, curNodeLevel + 1);
				queue.add(cur.left);
			}
			if (cur.right != null) {
				levelMap.put(cur.right, curNodeLevel + 1);
				queue.add(cur.right);
			}
			if (curNodeLevel == curLevel) {
				curLevelNodes++;
			} else {
				max = Math.max(max, curLevelNodes);
				curLevel++;
				curLevelNodes = 1;//已经有一个当前节点了
			}
		}
		max = Math.max(max, curLevelNodes);
		return max;
	}

 private static int findMax(TreeNode node) {
        if (node == null) {
            return 0;
        }
        LinkedList<TreeNode> nodes = new LinkedList<>();
        LinkedList<TreeNode> cache = new LinkedList<>();
        int max = -1;
        nodes.add(node);
        while (true) {
            while (!nodes.isEmpty()) {//一次倒空的循环
                max = Math.max(nodes.size(), max);
                TreeNode poll = nodes.poll();
                if (poll.left != null) {
                    cache.add(poll.left);
                }
                if (poll.right != null) {
                    cache.add(poll.right);
                }
            }
            if (cache.size() == 0) {
                break;//如果此时下一层已经没有了就没有必要继续了，直接跳出循环
            }
            LinkedList<TreeNode> tmp = nodes;//进行互换，这样子此时的nodes就变成了下一层的所有nodes
            nodes = cache;
            cache = tmp;
        }
        return max;
    }

  private static int findMax(TreeNode node) {
        if (node == null) {
            return 0;
        }
        int max = 1;
        LinkedList<TreeNode> nodes = new LinkedList<TreeNode>();
        LinkedList<Integer> list = new LinkedList<Integer>();
         list.add(0);
            
        nodes.offer(node);
        while(!nodes.isEmpty()){
        int count = nodes.size();
       
            for(;count>0;count--){
            TreeNode poll = nodes.poll();
            int curIndex = list.removeFirst();
            if(poll.left!=null){
                int left = curIndex*2+1;
                list.offer(left);
                nodes.offer(poll.left);
            }
            if(poll.right!=null){
                int right = curIndex*2+2;
                list.offer(right);
                nodes.offer(poll.right);
            }
            
            }
            if(list.size()>1){/// list 中 size 为 1 的情况下，宽度也为 1，没有必要计算。
              max = Math.max(max,list.getLast()-list.getFirst()+1);
            }
        }
        return max;
}