Add Vertical Order Traversal of a Binary Tree C#

Author: hellomrsun

August-LeetCoding-Challenge/07-Vertical-Order-Traversal-of-a-Binary-Tree/Vertical-Order-Traversal-of-a-Binary-Tree.cs

@@ -0,0 +1,60 @@
+public class Solution {
+    private int _minX = int.MaxValue;
+    private int _maxX = int.MinValue;
+    private int _minY = int.MaxValue;
+    private int _maxY = int.MinValue;
+    
+    public IList<IList<int>> VerticalTraversal(TreeNode root) {
+        var dict = new Dictionary<string, List<int>>();
+        Dfs(root, dict, 0, 0);
+        IList<IList<int>> res = new List<IList<int>>();
+        for(int i=_minX; i<=_maxX; i++){
+            var listY = new List<int>();
+            for(int j=_maxY; j>=_minY; j--){
+                var pos = i.ToString() + j.ToString();
+                if(dict.ContainsKey(pos)){
+                    var list = dict[pos];
+                    listY.AddRange(list);
+                }
+            }
+            if(listY.Count > 0){
+                res.Add(listY);
+            }
+        }
+        return res;
+    }
+    
+    private void Dfs(TreeNode root, Dictionary<string, List<int>> dict, int x, int y){
+        if(root == null) return;
+        var pos = x.ToString() + y.ToString();
+        if(dict.ContainsKey(pos)){
+            var list = dict[pos];
+            list.Add(root.val);
+            list.Sort();
+            dict[pos]=list;
+        }else {
+            dict[pos] = new List<int>{ root.val};
+        }
+        
+        _minX = Math.Min(_minX, x);
+        _maxX = Math.Max(_maxX, x);
+        _minY = Math.Min(_minY, y);
+        _maxY = Math.Max(_maxY, y);
+        Dfs(root.left, dict, x-1, y-1);
+        Dfs(root.right, dict, x+1, y-1);
+    }
+}
+
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */

README.md

@@ -13,6 +13,7 @@ Solutions in various programming languages are provided. Enjoy it.
 4. [Power of Four](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/04-Power-of-Four)
 5. [Add and Search Word Data structure design](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/05-Add-and-Search-Word-Data-structure-design)
 6. [Find All Duplicates in an Array](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/06-Find-All-Duplicates-in-an-Array)
+7. [Vertical Order Traversal of a Binary Tree](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/07-Vertical-Order-Traversal-of-a-Binary-Tree)
 
 ## July LeetCoding Challenge
 Click [here](https://leetcode.com/explore/featured/card/july-leetcoding-challenge/) for problem descriptions.