Merge pull request #2346 from eeee0717/master

Update 0106.添加C#版

problems/0106.从中序与后序遍历序列构造二叉树.md

@@ -1228,6 +1228,19 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+public TreeNode BuildTree(int[] inorder, int[] postorder)
+{
+    if (inorder.Length == 0 || postorder.Length == null) return null;
+    int rootValue = postorder.Last();
+    TreeNode root = new TreeNode(rootValue);
+    int delimiterIndex = Array.IndexOf(inorder, rootValue);
+    root.left = BuildTree(inorder.Take(delimiterIndex).ToArray(), postorder.Take(delimiterIndex).ToArray());
+    root.right = BuildTree(inorder.Skip(delimiterIndex + 1).ToArray(), postorder.Skip(delimiterIndex).Take(inorder.Length - delimiterIndex - 1).ToArray());
+    return root;
+}
+```
 
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problems/0617.合并二叉树.md

@@ -788,6 +788,20 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+public TreeNode MergeTrees(TreeNode root1, TreeNode root2)
+{
+    if (root1 == null) return root2;
+    if (root2 == null) return root1;
+
+    root1.val += root2.val;
+    root1.left = MergeTrees(root1.left, root2.left);
+    root1.right = MergeTrees(root1.right, root2.right);
+
+    return root1;
+}
+```
 
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problems/0654.最大二叉树.md

@@ -582,6 +582,21 @@ impl Solution {
     }
 }
 ```
+### C#
+```C#
+public TreeNode ConstructMaximumBinaryTree(int[] nums)
+{
+    if (nums.Length == 0) return null;
+    int rootValue = nums.Max();
+    TreeNode root = new TreeNode(rootValue);
+    int rootIndex = Array.IndexOf(nums, rootValue);
+
+    root.left = ConstructMaximumBinaryTree(nums.Take(rootIndex).ToArray());
+    root.right = ConstructMaximumBinaryTree(nums.Skip(rootIndex + 1).ToArray());
+    return root;
+
+}
+```
 
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