655. 输出二叉树

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方案一: DFS

var printTree = function(root) {
    // 单独求解出高度, 构造好 matrix, 然后再次遍历填入比较合适
    const calDepth = (root) => {
        let h = 0;
        if (root.left) {
            h = Math.max(h, calDepth(root.left) + 1);
        }
        if (root.right) {
            h = Math.max(h, calDepth(root.right) + 1);
        }
        return h;
    }

    const dfs = (res, root, r, c, height) => {
        res[r][c] = root.val.toString();
        if (root.left) {
            dfs(res, root.left, r + 1, c - (1 << (height - r - 1)), height);
        }
        if (root.right) {
            dfs(res, root.right, r + 1, c + (1 << (height - r - 1)), height);
        }
    }

    const height = calDepth(root);
    const m = height + 1;
    const n = (1 << (height + 1)) - 1;
    const res = new Array(m).fill(0).map(() => new Array(n).fill(''));
    dfs(res, root, 0, Math.floor((n - 1) / 2), height);
    return res;
};