314. Binary Tree Vertical Order Traversal

https://leetcode.com/problems/binary-tree-vertical-order-traversal/

Python

from collections import deque, defaultdict


class Solution:
    def verticalOrder(self, root: Optional[TreeNode]) -> List[List[int]]:
        mapper = defaultdict(list)
        queue = deque([(root, 0)])

        while queue:
            node, key = queue.popleft()

            if node:
                mapper[key].append(node.val)
                queue.append((node.left, key-1))
                queue.append((node.right, key+1))

        return [mapper[key] for key in sorted(mapper.keys())]

Javascript

var verticalOrder = function(root) {
    const queue = [];
    const res = {};
    let min = Infinity;

    if (root) queue.push([0, root]);
    while (queue.length) {
        const [idx, node] = queue.shift();

        min = Math.min(idx, min);

        if (res[idx]) res[idx].push(node.val);
        else res[idx] = [node.val];

        //console.log(idx, node.val);
        if (node.left) queue.push([idx - 1, node.left]);
        if (node.right) queue.push([idx + 1, node.right]);
    }

    const ary = [];
    while (res[min] !== undefined) {
        ary.push(res[min]);
        min++;
    }
    return ary;
};