js 实现二叉树的右侧视图

var rightSideView = function (root) {
    if (!root) {
        return [];
    }
    let res = [];
    let queue = [root];
    let count = 0;
    let finalRes = [];
    while (queue.length) {
        let len = queue.length;
        res[count] = [];
        while (len--) {
            const node = queue.shift();
            res[count].push(node.val);
            node.left && queue.push(node.left);
            node.right && queue.push(node.right);
        }
        count++;
    }
    res.forEach((item) => {
        finalRes.push(item.slice(-1));
    });
    return finalRes;
};