First Chapter

GitBook allows you to organize your book into chapters, each chapter is stored in a separate file like this one.

Analysis

Problems

public List<Integer> rightSideView(TreeNode root) {
        ArrayList<Integer> res = new ArrayList<Integer>();
        Queue<TreeNode> q = new LinkedList<TreeNode>();

        //corner case
        if(root==null) return res;

        //initial
        q.add(root);
        while(!q.isEmpty()) {
            int sizeOfq= q.size();
            for(int i=0; i<sizeOfq; i++) {
                TreeNode node = q.poll();
                if(node.left != null) q.add(node.left);
                if(node.right != null) q.add(node.right);
                if(i == sizeOfq-1) res.add(node.val);
            }
        }

        return res;
    }