diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index a22a93c..93495f5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.0)
 
+################################
+
 include_directories(core)
 include_directories(utils)
 include_directories(all_cases)
@@ -8,6 +10,10 @@ include_directories(raw_code)
 include_directories(short_code)
 include_directories(common_code)
 
+include_directories(fast_cal)
+
+################################
+
 add_subdirectory(core)
 add_subdirectory(utils)
 add_subdirectory(all_cases)
@@ -16,8 +22,13 @@ add_subdirectory(raw_code)
 add_subdirectory(short_code)
 add_subdirectory(common_code)
 
-#add_executable(klotski main.cc)
-add_executable(klotski main.cc fast_cal.cc)
+add_subdirectory(fast_cal)
+
+################################
+
+add_executable(klotski main.cc)
+
+################################
 
 target_link_libraries(klotski core)
 target_link_libraries(klotski utils)
@@ -27,4 +38,8 @@ target_link_libraries(klotski raw_code)
 target_link_libraries(klotski short_code)
 target_link_libraries(klotski common_code)
 
+target_link_libraries(klotski fast_cal)
+
 target_link_libraries(klotski pthread)
+
+################################
diff --git a/src/core/core.cc b/src/core/core.cc
index f459a80..e154935 100644
--- a/src/core/core.cc
+++ b/src/core/core.cc
@@ -173,7 +173,8 @@ void Core::next_step(uint64_t code, uint64_t mask) { // search next step cases
 
             // TODO: try to send multi-items data
             for (int i = 1; i < cache_size; ++i) {
-                release(cache[i].code, cache[i].mask); // release next cases
+//                release(cache[i].code, cache[i].mask); // release next cases
+                release_next(cache[i].code, cache[i].mask); // release next cases
             }
 
             cache_size = 1; // reset cache size
diff --git a/src/core/core.h b/src/core/core.h
index b3bfaf6..11a0d41 100644
--- a/src/core/core.h
+++ b/src/core/core.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdint>
+#include <functional>
 
 #define UP    (-4 * 3)
 #define LEFT  (-1 * 3)
@@ -10,10 +11,12 @@
 class Core {
 public:
 
-    typedef void (*release_t)(uint64_t, uint64_t);
+//    typedef void (*release_t)(uint64_t, uint64_t);
+
+    std::function<void(uint64_t, uint64_t)> release_next;
 
     void next_step(uint64_t code, uint64_t mask);
-    explicit Core(release_t release_func) : release(release_func) {}
+//    explicit Core(release_t release_func) : release(release_func) {}
 
 private:
     struct cache_t {
@@ -25,7 +28,7 @@ private:
 
     int cache_size = 1;
     cache_t cache[16] = {0};
-    release_t release; // release code and mask
+//    release_t release; // release code and mask
 
     void move_1x1(uint64_t code, int addr);
     void move_1x2(uint64_t code, int addr);
diff --git a/src/fast_cal.h b/src/fast_cal.h
deleted file mode 100644
index 939365e..0000000
--- a/src/fast_cal.h
+++ /dev/null
@@ -1,5 +0,0 @@
-#pragma once
-
-#include <cstdint>
-
-uint32_t fast_cal(uint64_t start_code);
diff --git a/src/fast_cal/CMakeLists.txt b/src/fast_cal/CMakeLists.txt
new file mode 100644
index 0000000..5b21746
--- /dev/null
+++ b/src/fast_cal/CMakeLists.txt
@@ -0,0 +1,4 @@
+cmake_minimum_required(VERSION 3.0)
+
+add_library(fast_cal fast_cal.cc)
+target_link_libraries(fast_cal core)
diff --git a/src/fast_cal/fast_cal.cc b/src/fast_cal/fast_cal.cc
new file mode 100644
index 0000000..acd7e5c
--- /dev/null
+++ b/src/fast_cal/fast_cal.cc
@@ -0,0 +1,65 @@
+#include "core.h"
+#include "common.h"
+#include "fast_cal.h"
+
+#include "raw_code.h"
+
+#include <iostream>
+
+void FastCal::fast_cal(uint64_t code) {
+
+    std::cout << RawCode(code).dump_case() << std::endl;
+
+    auto core = Core();
+    core.release_next = std::bind(&FastCal::add_new_case, this, std::placeholders::_1, std::placeholders::_2);
+
+    cases.empty();
+    cache.empty();
+
+    cases[code] = fast_cal_t {
+        .code = code,
+        .mask = 0,
+        .last = nullptr,
+    };
+    cache.emplace(&cases[code]);
+
+    while (!cache.empty()) {
+
+        // break check point
+        if (((cache.front()->code >> (3 * 0xD)) & 0b111) == B_2x2) {
+            std::cout << "Resolved" << std::endl;
+//            std::cout << RawCode(cache.front()->code).dump_case() << std::endl;
+            break;
+        }
+
+        core.next_step(cache.front()->code, cache.front()->mask);
+        cache.pop();
+    }
+
+    auto solution = cache.front();
+
+    while (solution != nullptr) {
+//        std::cout << RawCode(solution->code).dump_case() << std::endl;
+        solution = solution->last;
+    }
+
+}
+
+void FastCal::add_new_case(uint64_t code, uint64_t mask) {
+
+    auto exist_case = cases.find(code);
+    if (exist_case != cases.end()) { // find existed case
+
+        exist_case->second.mask |= mask; // mask update
+        return;
+
+    }
+
+    cases[code] = fast_cal_t {
+            .code = code,
+            .mask = mask,
+            .last = cache.front(),
+    };;
+    cache.emplace(&cases[code]);
+
+}
diff --git a/src/fast_cal/fast_cal.h b/src/fast_cal/fast_cal.h
new file mode 100644
index 0000000..f8dbc68
--- /dev/null
+++ b/src/fast_cal/fast_cal.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <queue>
+#include <cstdint>
+#include <unordered_map>
+
+class FastCal {
+public:
+    struct fast_cal_t {
+        uint64_t code;
+        uint64_t mask;
+        fast_cal_t *last;
+    };
+
+    std::queue<fast_cal_t*> cache;
+    std::unordered_map<uint64_t, fast_cal_t> cases;
+
+    void fast_cal(uint64_t code);
+
+    void add_new_case(uint64_t code, uint64_t mask);
+
+};
diff --git a/src/main.cc b/src/main.cc
index 4b1222f..5154e46 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -194,7 +194,9 @@ int main() {
 //    }
 
     auto raw_code = CommonCode("1a9bf0c").to_raw_code().unwrap();
-    std::cout << fast_cal(raw_code) << std::endl;
+//    std::cout << fast_cal(raw_code) << std::endl;
+    auto f = FastCal();
+    f.fast_cal(raw_code);
 
 //    int sum = 0;
 //    for (auto const &raw_code : all_cases_raw) {