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$ curl repovive.com/roadmaps/meta-interview-prep-v2/coding-patterns-ii-trees-graphs-advanced/leetcode-314-binary-tree-vertical-order-traversal-implementation

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$ curl repovive.com/roadmaps/meta-interview-prep-v2/coding-patterns-ii-trees-graphs-advanced/leetcode-314-binary-tree-vertical-order-traversal-implementation

Repovive

LeetCode 314 Binary Tree Vertical Order Traversal - Implementation - Coding Patterns II: Trees, Graphs & Advanced | Meta Interview Prep | Repovive

Repovive.

Meta Interview Prep6 sections · 147 units8h total

Open in Course

LeetCode 314 Binary Tree Vertical Order Traversal - Implementation

The approach

function verticalOrder(root):
    if not root:
        return []
    colMap = defaultdict(list)
    queue = deque([(root, 0)])
    while queue:
        node, col = queue.popleft()
        colMap[col].append(node.val)
        if node.left:
            queue.append((node.left, col - 1))
        if node.right:
            queue.append((node.right, col + 1))
    return [colMap[c] for c in sorted(colMap.keys())]

$O(n \log n)$ time due to sorting column keys. $O(n)$ space for the map and queue.