add 987

Author: MatNoble

LeetCodeSolutions/987.py

@@ -0,0 +1,49 @@
+#==================================================
+#==>      Title:                                     
+#==>     Author: Zhang zhen                   
+#==>      Email: hustmatnoble.gmail.com
+#==>     GitHub: https://github.com/MatNoble
+#==>       Date: 
+#==================================================
+
+from typing import List
+import collections
+# 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]]:     
+        vertical = collections.defaultdict(list)
+
+        queue = collections.deque()
+        queue.append((root, 0, 0))
+        while queue:
+            node, row, col = queue.popleft()
+            vertical[col].append([row, node.val])
+            if node.left:
+                queue.append((node.left, row+1, col-1))
+            if node.right:
+                queue.append((node.right, row+1, col+1))
+        # def dfs(node,row=0,col=0):
+        #     if node is None: return None
+        #     dfs(node.left  ,row+1,col-1)
+        #     dfs(node.right ,row+1,col+1)
+        #     vertical[col].append([row, node.val]) 
+        # dfs(root)
+        return [ [node_value for row_value, node_value in sorted(values)] for col_value, values in sorted(vertical.items())]
+
+
+root = TreeNode(1)
+root.left = TreeNode(2)
+root.right = TreeNode(3)
+root.left.left = TreeNode(4)
+root.left.right = TreeNode(6)
+root.right.left = TreeNode(5)
+root.right.right = TreeNode(7)
+
+mat = Solution()
+mat.verticalTraversal(root)