diff --git a/assignment1/problem3/struct.h b/assignment1/problem3/struct.h
index 4110002..8126d73 100644
--- a/assignment1/problem3/struct.h
+++ b/assignment1/problem3/struct.h
@@ -23,7 +23,7 @@ typedef struct ASTString_str {
 
 } ASTString;
 
-/* AST Node structure, describe in ./README.md */
+/* AST Node structure */
 typedef struct ASTNode_str {
 
 	/* 1: string, 2: left (, 3: right ) */
diff --git a/assignment1/problem3/uncompress.c b/assignment1/problem3/uncompress.c
index bf2ad89..83c07e1 100644
--- a/assignment1/problem3/uncompress.c
+++ b/assignment1/problem3/uncompress.c
@@ -1,3 +1,10 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Assignment_1_Problem_3
+ * uncompress using AST method
+ */
+
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
diff --git a/assignment1/problem3/uncompress.h b/assignment1/problem3/uncompress.h
index 1a52844..cb79b19 100644
--- a/assignment1/problem3/uncompress.h
+++ b/assignment1/problem3/uncompress.h
@@ -1,3 +1,32 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Assignment_1_Problem_3
+ *
+ * AST (Abstract Syntax Tree) is a tree representation of the abstract
+ * syntactic structure of source code written in a programming language.
+ * Each node of the tree denotes a construct occurring in the source code.
+ *
+ * First of all, ASTScanner can scan the source code with LL(1) parser,
+ * return a token (ASTNode) of source code, there are 3 types of token.
+ * 1: string
+ * 2: loop start with repeat times
+ * 3: end loop
+ *
+ * Then ASTScanAll() can take all token into tree.
+ *
+ * For example:
+ * source code start3(miku6(aaa)asdf)end will generate the following tree:
+ *
+ * "start" -> 3 -> "end"
+ *            |
+ *            -> "miku" -> 6 -> "asdf"
+ *                         |
+ *                         -> "aaa" 
+ *
+ * ASTCompileTree() can compile the tree into output.
+ */
+
 #ifndef UNCOMPRESS
 #define UNCOMPRESS