Print Binary Tree.java

// Runtime: 1 ms (Top 100.00%) | Memory: 43.8 MB (Top 78.96%)
class Solution {
    public List<List<String>> printTree(TreeNode root) {
        List<List<String>> res = new ArrayList();

        int height = getHeight(root);
        int row = height + 1;
        int column = (int) Math.pow(2, height+1) - 1;

        for(int k=0; k<row; k++){
            List<String> list = new ArrayList();
            for(int i=0; i<column; i++){
                list.add("");
            }
            res.add(list);
        }

        int left = 0;
        int right = column-1;
        int level=0;
        print(res, left, right, level, root);

        return res;
    }
    public void print(List<List<String>> res, int left, int right, int level, TreeNode root){
        if(root == null) return;
        int mid = left+(right-left)/2;
        res.get(level).set(mid, String.valueOf(root.val));

        print(res, left, mid-1, level+1, root.left);
        print(res, mid+1, right, level+1, root.right);
    }
    public int getHeight(TreeNode root){
        if (root==null) return -1;
        int left = getHeight(root.left);
        int right = getHeight(root.right);

        return Math.max(left, right)+1;
    }
}