Merge pull request #277 from hellomrsun/master

Add Delete-Node-in-a-BST C#

Author: hellomrsun

August-LeetCoding-Challenge/31-Delete-Node-in-a-BST/Delete-Node-in-a-BST.cs

@@ -0,0 +1,43 @@
+public class Solution {
+    public TreeNode DeleteNode(TreeNode root, int key) {
+        if(root == null) return null;
+        if(key < root.val){
+            root.left = DeleteNode(root.left, key);
+        }else if(key > root.val){
+            root.right = DeleteNode(root.right, key);
+        }else{
+            if(root.left == null)
+            {
+                return root.right;
+            }
+            else if(root.right == null){
+                return root.left;
+            }
+            
+            var minNode = FindMin(root.right);
+            root.val = minNode.val;
+            root.right = DeleteNode(root.right, root.val);
+        }
+        return root;
+    }
+    
+    public TreeNode FindMin(TreeNode node){
+        while(node.left != null){
+            node = node.left;
+        }
+        return node;
+    }
+}
+/**
+ * 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

@@ -37,6 +37,8 @@ Solutions in various programming languages are provided. Enjoy it.
 28. [Implement Rand10() Using Rand7()](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/28-Implement-Rand10()-Using-Rand7())
 29. [Pancake Sorting](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/29-Pancake-Sorting)
 30. [Largest Component Size by Common Factor](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/30-Largest-Component-Size-by-Common-Factor)
+31. [Delete Node in a BST](https://github.com/AlgoStudyGroup/Leetcode/tree/master/August-LeetCoding-Challenge/31-Delete-Node-in-a-BST)
+
 
 ## July LeetCoding Challenge
 Click [here](https://leetcode.com/explore/featured/card/july-leetcoding-challenge/) for problem descriptions.