Added solution for https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/

Author: fspv

l33tcode/vertical-order-traversal-of-a-binary-tree.py

@@ -0,0 +1,46 @@
+import heapq
+from typing import List, Tuple
+from collections import defaultdict, deque
+
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+class Solution:
+    def verticalTraversal(self, root: TreeNode) -> List[List[int]]:
+        def dfs(
+            node: TreeNode, row: int, col: int, heap: List[Tuple[int, int, int]]
+        ) -> None:
+            heapq.heappush(heap, (col, row, node.val))
+            if node.left:
+                dfs(node.left, row + 1, col - 1, heap)
+            if node.right:
+                dfs(node.right, row + 1, col + 1, heap)
+
+        if not root:
+            return []
+
+        heap: List[Tuple[int, int, int]] = []
+
+        dfs(root, 0, 0, heap)
+
+        result: List[List[int]] = []
+
+        col_prev = float("-inf")  # row 1 does not exist
+
+        while heap:
+            col, row, val = heapq.heappop(heap)
+
+            if col != col_prev:
+                result.append([])
+
+            result[-1].append(val)
+
+            col_prev = col
+
+        return result