cousins-in-binary-tree-ii

var replaceValueInTree = function (root) {
    function dfs(arr) {
        if (arr.length == 0) return

        let sum = 0

        for (let node of arr) {
            if (!node) continue
            if (node.left) sum += node.left.val
            if (node.right) sum += node.right.val
        }

        let childArr = []

        for (let node of arr) {
            let curSum = 0

            if (node.left) curSum += node.left.val
            if (node.right) curSum += node.right.val

            if (node.left) {
                node.left.val = sum - curSum
                childArr.push(node.left)
            }
            if (node.right) {
                node.right.val = sum - curSum
                childArr.push(node.right)
            }
        }

        dfs(childArr)
    }

    root.val = 0
    dfs([root])

    return root
};