diff --git a/homework.cpp b/homework.cpp
index 18fbb13..3d1700f 100644
--- a/homework.cpp
+++ b/homework.cpp
@@ -1,20 +1,13 @@
-#include<iostream>
-
+#include <iostream>
 using namespace std;
 
-int main(){
-    int daxie=65,xiaoxie=97;
-    while (daxie != 91 and xiaoxie != 123)
-    {
-        char daxie_1 = daxie;
-        char xiaaoxie_1 = xiaoxie;
-
-        cout <<daxie_1<<xiaaoxie_1;
-
-        daxie++;
-        xiaoxie++;
+int main() {
+    // 遍历1到200的所有数
+    for (int i = 1; i <= 200; i++) {
+        // 判断该数是否满足"3721"数的条件
+        if (i % 3 == 2 && i % 7 == 1) {
+            cout << i << " ";  // 输出满足条件的数
+        }
     }
-    
-    
     return 0;
-}
\ No newline at end of file
+}
diff --git a/homework_1.cpp b/old_homework/12.21.cpp
similarity index 100%
rename from homework_1.cpp
rename to old_homework/12.21.cpp
diff --git a/old_homework/12.28.cpp b/old_homework/12.28.cpp
new file mode 100644
index 0000000..18fbb13
--- /dev/null
+++ b/old_homework/12.28.cpp
@@ -0,0 +1,20 @@
+#include<iostream>
+
+using namespace std;
+
+int main(){
+    int daxie=65,xiaoxie=97;
+    while (daxie != 91 and xiaoxie != 123)
+    {
+        char daxie_1 = daxie;
+        char xiaaoxie_1 = xiaoxie;
+
+        cout <<daxie_1<<xiaaoxie_1;
+
+        daxie++;
+        xiaoxie++;
+    }
+    
+    
+    return 0;
+}
\ No newline at end of file