【leetcode】637.二叉树的层平均值

leetcode-637.png

又是一题层次遍历

var averageOfLevels = function (root) {
    if (!root) return []
    let res = []
    let queue = []
    queue.push(root)
    while (queue.length) {
        let size = queue.length
        let sum = 0
        for (let i = 0; i < size; ++i) {
            let node = queue.shift()
            sum += node.val
            if (node.left) queue.push(node.left)
            if (node.right) queue.push(node.right)
        }
        res.push(sum / size)
    }
    return res
};