diff --git a/src/klotski_core/CMakeLists.txt b/src/klotski_core/CMakeLists.txt
index 216e42f..8760e69 100644
--- a/src/klotski_core/CMakeLists.txt
+++ b/src/klotski_core/CMakeLists.txt
@@ -104,6 +104,12 @@ include_directories(group)
 
 ################################################################################
 
+find_package(absl REQUIRED)
+
+find_package(unordered_dense CONFIG REQUIRED)
+
+################################################################################
+
 add_subdirectory(utils)
 add_subdirectory(all_cases)
 
@@ -151,4 +157,7 @@ else()
     add_library(klotski STATIC ${OBJS})
 endif()
 
+target_link_libraries(klotski absl::flat_hash_map)
+target_link_libraries(klotski unordered_dense::unordered_dense)
+
 ################################################################################
diff --git a/src/klotski_core/ffi/tmain.cc b/src/klotski_core/ffi/tmain.cc
index d860c33..1f4f0e7 100644
--- a/src/klotski_core/ffi/tmain.cc
+++ b/src/klotski_core/ffi/tmain.cc
@@ -31,14 +31,32 @@ void tmain() {
 //    Group::block_num(CommonCode(0x4FEA13400));
 //    Group::block_num(RawCode::from_common_code(0x4FEA13400));
 
-    for (auto &&common_code : AllCases::release()) {
-        auto s1 = Group::block_num(common_code);
-        auto s2 = Group::block_num(common_code.to_raw_code());
-        if (s1.n_1x1 != s2.n_1x1 || s1.n_1x2 != s2.n_1x2 || s1.n_2x1 != s2.n_2x1) {
-            std::cout << "fuck" << std::endl;
-        }
+//    for (auto &&common_code : AllCases::release()) {
+//        auto s1 = Group::block_num(common_code);
+//        auto s2 = Group::block_num(common_code.to_raw_code());
+//        if (s1.n_1x1 != s2.n_1x1 || s1.n_1x2 != s2.n_1x2 || s1.n_2x1 != s2.n_2x1) {
+//            std::cout << "fuck" << std::endl;
+//        }
+//    }
+
+    auto cases = std::vector<RawCode>();
+    auto common_codes = AllCases::release();
+    for (uint64_t i = 0; i < common_codes.size(); i += 293345 * 2) {
+        cases.emplace_back(common_codes[i].to_raw_code());
     }
 
+    std::cout << "select " << cases.size() << " cases" << std::endl;
+
+    auto start = clock();
+
+    for (auto &&raw_code : cases) {
+        std::cout << Group::demo(raw_code) << std::endl;
+    }
+
+//    Group::demo(RawCode::from_common_code(0x1A9BF0C00));
+//    Group::demo(RawCode::from_common_code(0x4FEA13400));
+
+    std::cout << ((clock() - start) * 1000 / CLOCKS_PER_SEC) << "ms" << std::endl;
 
     return;
 
@@ -136,7 +154,7 @@ void tmain() {
 
     std::cout << "start search" << std::endl;
 
-    auto start = clock();
+//    auto start = clock();
 
     for (const auto &c : all_cases) {
 
diff --git a/src/klotski_core/group/CMakeLists.txt b/src/klotski_core/group/CMakeLists.txt
index 2ba2948..da26c26 100644
--- a/src/klotski_core/group/CMakeLists.txt
+++ b/src/klotski_core/group/CMakeLists.txt
@@ -1,3 +1,7 @@
 cmake_minimum_required(VERSION 3.0)
 
+find_package(unordered_dense CONFIG REQUIRED)
+
 add_library(group OBJECT group.cc)
+
+target_link_libraries(group unordered_dense::unordered_dense)
diff --git a/src/klotski_core/group/group.cc b/src/klotski_core/group/group.cc
index 8e03ad8..8dea2d4 100644
--- a/src/klotski_core/group/group.cc
+++ b/src/klotski_core/group/group.cc
@@ -1,6 +1,15 @@
+#include <queue>
 #include <iostream>
+
+//#include <map>
+//#include <unordered_map>
+//#include <boost/unordered_map.hpp>
+//#include <ankerl/unordered_dense.h>
+#include "absl/container/flat_hash_map.h"
+
 #include "group.h"
 #include "common.h"
+#include "core.h"
 
 namespace klotski {
 
@@ -44,6 +53,61 @@ Group::block_num_t Group::block_num(const CommonCode &common_code) {
     return result;
 }
 
+//struct custom_hash_simple {
+//
+//    using is_avalanching = void;
+//
+//    auto operator()(uint64_t const& x) const noexcept -> uint64_t {
+//        return ankerl::unordered_dense::detail::wyhash::hash(static_cast<uint64_t>(x));
+//    }
+//};
+
+uint32_t Group::demo(const RawCode &seed) {
+    struct group_cal_t {
+        uint64_t code;
+        uint64_t mask;
+    };
+
+    std::queue<group_cal_t*> cache;
+
+//    std::map<uint64_t, group_cal_t> cases;
+//    std::unordered_map<uint64_t, group_cal_t> cases;
+//    boost::unordered_map<uint64_t, group_cal_t> cases;
+//    ankerl::unordered_dense::map<uint64_t, group_cal_t> cases;
+    absl::flat_hash_map<uint64_t, group_cal_t> cases;
+
+    cases.reserve(65535 * 8);
+
+    cache.emplace(&cases.emplace(seed.unwrap(), group_cal_t {
+        .code = seed.unwrap(),
+        .mask = 0,
+    }).first->second);
+
+    auto core = Core(
+        [&cases, &cache](auto &&code, auto &&mask) {
+            auto current = cases.find(code);
+
+            if (current != cases.end()) { // find existed case
+                current->second.mask |= mask; // update mask info
+                return;
+            }
+
+            cache.emplace(&cases.emplace(code, group_cal_t {
+                .code = code,
+                .mask = mask,
+            }).first->second);
+        }
+    );
+
+    while (!cache.empty()) {
+        core.next_cases(cache.front()->code, cache.front()->mask);
+        cache.pop();
+    }
+
+//    std::cout << cases.size() << std::endl;
+
+    return cases.size();
+}
 
 
 } // namespace klotski
diff --git a/src/klotski_core/group/group.h b/src/klotski_core/group/group.h
index 2a6cce5..9a3e184 100644
--- a/src/klotski_core/group/group.h
+++ b/src/klotski_core/group/group.h
@@ -18,6 +18,8 @@ public:
     static block_num_t block_num(const RawCode &raw_code);
     static block_num_t block_num(const CommonCode &common_code);
 
+    static uint32_t demo(const RawCode &seed);
+
 };
 
 }