feat: add go solution to lc problem: No.0114 (doocs#842)

No.0114.Flatten Binary Tree to Linked List

Author: poltao

solution/0100-0199/0114.Flatten Binary Tree to Linked List/README.md

@@ -194,6 +194,33 @@ public:
 };
 ```
 
+### **Go**
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func flatten(root *TreeNode) {
+	for root != nil {
+		left, right := root.Left, root.Right
+		root.Left = nil
+		if left != nil {
+			root.Right = left
+			for left.Right != nil {
+				left = left.Right
+			}
+			left.Right = right
+		}
+		root = root.Right
+	}
+}
+```
+
 ### **...**
 
 ```

solution/0100-0199/0114.Flatten Binary Tree to Linked List/README_EN.md

@@ -178,6 +178,33 @@ public:
 };
 ```
 
+### **Go**
+
+```go
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func flatten(root *TreeNode) {
+	for root != nil {
+		left, right := root.Left, root.Right
+		root.Left = nil
+		if left != nil {
+			root.Right = left
+			for left.Right != nil {
+				left = left.Right
+			}
+			left.Right = right
+		}
+		root = root.Right
+	}
+}
+```
+
 ### **...**
 
 ```

solution/0100-0199/0114.Flatten Binary Tree to Linked List/Solution.go

@@ -0,0 +1,22 @@
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func flatten(root *TreeNode) {
+	for root != nil {
+		left, right := root.Left, root.Right
+		root.Left = nil
+		if left != nil {
+			root.Right = left
+			for left.Right != nil {
+				left = left.Right
+			}
+			left.Right = right
+		}
+		root = root.Right
+	}
+}