计算二叉树节点的个数

[unliar]

const countNodes = function (root) {
    if (!root) return 0;
    const queqe = [root];
    let count = 0;
    while (queqe.length > 0) {
        let p = queqe.shift();
        count++;
        if (p.left) queqe.push(p.left);
        if (p.right) queqe.push(p.right);
    }
    return count;
};