diff --git a/src/klotski/all_cases/all_cases.cc b/src/klotski/all_cases/all_cases.cc
index 7f8e5b7..4a8bc78 100644
--- a/src/klotski/all_cases/all_cases.cc
+++ b/src/klotski/all_cases/all_cases.cc
@@ -1,12 +1,7 @@
 #include "common.h"
 #include "all_cases.h"
 
-const uint32_t ALL_CASES_SIZE[16] = {
-    2942906, 2260392, 2942906, 0,
-    2322050, 1876945, 2322050, 0,
-    2322050, 1876945, 2322050, 0,
-    2942906, 2260392, 2942906, 0,
-};
+using namespace klotski;
 
 /// static variable initialize
 std::mutex AllCases::building;
diff --git a/src/klotski/all_cases/all_cases.h b/src/klotski/all_cases/all_cases.h
index 936a473..8e0fb0d 100644
--- a/src/klotski/all_cases/all_cases.h
+++ b/src/klotski/all_cases/all_cases.h
@@ -5,16 +5,26 @@
 #include <cstdint>
 #include "basic_ranges.h"
 
-class AllCases : public BasicRanges {
-public:
-    static void build();
-    static enum Status status();
-    static const std::vector<uint32_t> (&fetch())[16];
+namespace klotski {
+    /// all cases count
+    const uint32_t ALL_CASES_SIZE[16] = {
+        2942906, 2260392, 2942906, 0,
+        2322050, 1876945, 2322050, 0,
+        2322050, 1876945, 2322050, 0,
+        2942906, 2260392, 2942906, 0,
+    };
 
-private:
-    static bool available;
-    static std::mutex building;
-    static std::vector<uint32_t> data[16];
+    class AllCases : public BasicRanges {
+    public:
+        static void build();
+        static enum Status status();
+        static const std::vector<uint32_t> (&fetch())[16];
 
-    static void build_data();
-};
+    private:
+        static bool available;
+        static std::mutex building;
+        static std::vector<uint32_t> data[16];
+
+        static void build_data();
+    };
+}
diff --git a/src/klotski/all_cases/basic_ranges.cc b/src/klotski/all_cases/basic_ranges.cc
index eed55b1..d9c7608 100644
--- a/src/klotski/all_cases/basic_ranges.cc
+++ b/src/klotski/all_cases/basic_ranges.cc
@@ -3,7 +3,7 @@
 #include "common.h"
 #include "basic_ranges.h"
 
-const uint32_t BASIC_RANGES_SIZE = 7311921;
+using namespace klotski;
 
 /// static variable initialize
 std::mutex BasicRanges::building;
diff --git a/src/klotski/all_cases/basic_ranges.h b/src/klotski/all_cases/basic_ranges.h
index 2b86c89..6c03aaf 100644
--- a/src/klotski/all_cases/basic_ranges.h
+++ b/src/klotski/all_cases/basic_ranges.h
@@ -4,29 +4,34 @@
 #include <vector>
 #include <cstdint>
 
-class BasicRanges {
-public:
-    enum Status {
-        NO_INIT,
-        BUILDING,
-        AVAILABLE,
-    };
-    static void build();
-    static enum Status status();
-    static const std::vector<uint32_t>& fetch();
+namespace klotski {
+    /// basic ranges count
+    const uint32_t BASIC_RANGES_SIZE = 7311921;
 
-private:
-    struct generate_t {
-        int n1; // number of `00`
-        int n2; // number of `01`
-        int n3; // number of `10`
-        int n4; // number of `11`
-    };
+    class BasicRanges {
+    public:
+        enum Status {
+            NO_INIT,
+            BUILDING,
+            AVAILABLE,
+        };
+        static void build();
+        static enum Status status();
+        static const std::vector<uint32_t> &fetch();
 
-    static bool available;
-    static std::mutex building;
-    static std::vector<uint32_t> data;
+    private:
+        struct generate_t {
+            int n1; // number of `00`
+            int n2; // number of `01`
+            int n3; // number of `10`
+            int n4; // number of `11`
+        };
 
-    static void build_data();
-    static void generate(generate_t info);
-};
+        static bool available;
+        static std::mutex building;
+        static std::vector<uint32_t> data;
+
+        static void build_data();
+        static void generate(generate_t info);
+    };
+}
diff --git a/src/klotski/common_code/common_code.cc b/src/klotski/common_code/common_code.cc
index 3a3101e..14d6771 100644
--- a/src/klotski/common_code/common_code.cc
+++ b/src/klotski/common_code/common_code.cc
@@ -2,6 +2,8 @@
 #include "common.h"
 #include "common_code.h"
 
+using namespace klotski;
+
 uint64_t CommonCode::unwrap() const {
     return code; // raw uint64_t code
 }
diff --git a/src/klotski/ffi/tmain.cc b/src/klotski/ffi/tmain.cc
index ee69004..1b0b65e 100644
--- a/src/klotski/ffi/tmain.cc
+++ b/src/klotski/ffi/tmain.cc
@@ -14,7 +14,7 @@ void tmain() {
 
     uint64_t common_code = 0x1A9BC0C00;
 
-    Common::range_reverse(common_code);
+    klotski::Common::range_reverse(common_code);
 
 //    uint64_t raw_code = 0x0603EDF5CAFFF5E2;
 
diff --git a/src/klotski/raw_code/convert.cc b/src/klotski/raw_code/convert.cc
index a361b78..ee3ff55 100644
--- a/src/klotski/raw_code/convert.cc
+++ b/src/klotski/raw_code/convert.cc
@@ -2,6 +2,8 @@
 #include "common.h"
 #include "raw_code.h"
 
+using namespace klotski;
+
 /// RawCode to CommonCode
 CommonCode RawCode::to_common_code() const {
     if (!RawCode::check(code)) {
diff --git a/src/klotski/short_code/convert.cc b/src/klotski/short_code/convert.cc
index c90dca0..ed6306d 100644
--- a/src/klotski/short_code/convert.cc
+++ b/src/klotski/short_code/convert.cc
@@ -6,6 +6,8 @@
 #include "basic_ranges_offset.h"
 #include "range_prefix_offset.h"
 
+using namespace klotski;
+
 /// ShortCode to CommonCode
 CommonCode ShortCode::to_common_code() const { // convert to common code
     if (ShortCode::mode() == ShortCode::NORMAL) {
diff --git a/src/klotski/short_code/short_code.cc b/src/klotski/short_code/short_code.cc
index 6bdb385..397a331 100644
--- a/src/klotski/short_code/short_code.cc
+++ b/src/klotski/short_code/short_code.cc
@@ -1,6 +1,8 @@
 #include "all_cases.h"
 #include "short_code.h"
 
+using namespace klotski;
+
 uint32_t ShortCode::unwrap() const {
     return code; // raw uint32_t code
 }
diff --git a/src/klotski/utils/common.cc b/src/klotski/utils/common.cc
index 6c12042..9535140 100644
--- a/src/klotski/utils/common.cc
+++ b/src/klotski/utils/common.cc
@@ -1,5 +1,7 @@
 #include "common.h"
 
+using namespace klotski;
+
 uint32_t Common::range_reverse(uint32_t bin) { // reverse binary every 2-bits
     bin = ((bin << 16) & 0xFFFF0000) | ((bin >> 16) & 0x0000FFFF);
     bin = ((bin << 8) & 0xFF00FF00) | ((bin >> 8) & 0x00FF00FF);
diff --git a/src/klotski/utils/common.h b/src/klotski/utils/common.h
index 5b4006d..b103572 100644
--- a/src/klotski/utils/common.h
+++ b/src/klotski/utils/common.h
@@ -59,8 +59,10 @@
 ///   00 01 10 11 ...  =>  ... 11 10 01 00
 ///   (high 8-bits)           (low 8-bits)
 
-class Common {
-public:
-    static uint32_t range_reverse(uint32_t bin);
-    static uint8_t check_range(uint32_t head, uint32_t range);
-};
+namespace klotski {
+    class Common {
+    public:
+        static uint32_t range_reverse(uint32_t bin);
+        static uint8_t check_range(uint32_t head, uint32_t range);
+    };
+}