diff --git a/src/analyse/analyse.cc b/src/analyse/analyse.cc
index 66e7f84..2a51ad9 100644
--- a/src/analyse/analyse.cc
+++ b/src/analyse/analyse.cc
@@ -2,6 +2,7 @@
 #include "analyse.h"
 
 #include <iostream>
+#include "raw_code.h"
 
 Core Analyse::new_core() {
     return Core(
@@ -11,6 +12,20 @@ Core Analyse::new_core() {
     );
 }
 
+void Analyse::backtrack(uint64_t code) {
+
+    // backtrack start at code
+    std::cout << "start backtrack" << std::endl;
+
+    std::cout << RawCode(code).dump_case() << std::endl;
+    std::cout << "src size: " << cases[code].src.size() << std::endl;
+
+    auto last_1 = cases[code].src.front();
+    std::cout << RawCode(last_1->code).dump_case() << std::endl;
+    std::cout << "src size: " << last_1->src.size() << std::endl;
+
+}
+
 void Analyse::start_analyse(uint64_t code) {
 
     auto core = new_core();
@@ -24,6 +39,7 @@ void Analyse::start_analyse(uint64_t code) {
         .code = code,
         .mask = 0,
         .step = 0,
+//        .highlight = false,
 //        .src = std::move(std::list<analyse_t*>{}),
     }).first->second);
 
@@ -40,39 +56,41 @@ void Analyse::start_analyse(uint64_t code) {
 void Analyse::new_case(uint64_t code, uint64_t mask) {
 
 
-    auto temp = cases.emplace(code, analyse_t {
-        .code = code,
-        .mask = mask,
-        .step = cache.front()->step + 1,
-        .src = std::move(std::list<analyse_t*>{cache.front()})
-    });
+//    auto temp = cases.emplace(code, analyse_t {
+//        .code = code,
+//        .mask = mask,
+//        .step = cache.front()->step + 1,
+//        .src = std::move(std::list<analyse_t*>{cache.front()})
+//    });
+//
+//    if (temp.second) {
+//        cache.emplace(&temp.first->second);
+//    } else {
+//        temp.first->second.mask |= mask;
+//
+//        if (temp.first->second.step != cache.front()->step) {
+//            temp.first->second.src.push_back(cache.front());
+//        }
+//
+//    }
 
-    if (temp.second) {
-        cache.emplace(&temp.first->second);
-    } else {
-        temp.first->second.mask |= mask;
+    auto current = cases.find(code);
+    if (current != cases.end()) { // find existed case
+        current->second.mask |= mask; // update mask info
 
-        if (temp.first->second.step != cache.front()->step) {
-            temp.first->second.src.push_back(cache.front());
+        if (current->second.step != cache.front()->step) {
+            current->second.src.push_back(cache.front());
         }
 
+        return;
     }
 
-//    auto current = cases.find(code);
-//    if (current != cases.end()) { // find existed case
-//        current->second.mask |= mask; // update mask info
-//
-//        if (current->second.step != cache.front()->step) {
-//            current->second.src.push_back(cache.front());
-//        }
-//
-//        return;
-//    }
-//
-//    cache.emplace(&cases.emplace(code, analyse_t {
-//        .code = code,
-//        .mask = mask,
-//        .step = cache.front()->step + 1,
-//        .src = std::move(std::list<analyse_t*>{cache.front()}),
-//    }).first->second);
+    cache.emplace(&cases.emplace(code, analyse_t {
+        .code = code,
+        .mask = mask,
+        .step = cache.front()->step + 1,
+//        .highlight = false,
+        .src = std::move(std::list<analyse_t*>{cache.front()}),
+    }).first->second);
+
 }
diff --git a/src/analyse/analyse.h b/src/analyse/analyse.h
index 7d438b2..92adc3d 100644
--- a/src/analyse/analyse.h
+++ b/src/analyse/analyse.h
@@ -16,17 +16,27 @@ public:
 
         int step;
 
+//        bool highlight;
+
 //        std::vector<analyse_t*> src;
         std::list<analyse_t*> src;
 //        std::set<analyse_t*> src;
 //        std::unordered_set<analyse_t*> src;
     };
 
+    struct backtrack_t {
+        uint64_t code;
+        std::list<backtrack_t*> next;
+    };
+
     std::queue<analyse_t*> cache;
     std::unordered_map<uint64_t, analyse_t> cases;
 
     inline Core new_core();
 
+    // TODO: backtrack for multi-codes
+    void backtrack(uint64_t code);
+
     void start_analyse(uint64_t code);
 
     void new_case(uint64_t code, uint64_t mask);
diff --git a/src/fast_cal/fast_cal.cc b/src/fast_cal/fast_cal.cc
index 269f78a..0d6250c 100644
--- a/src/fast_cal/fast_cal.cc
+++ b/src/fast_cal/fast_cal.cc
@@ -88,6 +88,7 @@ void FastCal::fast_cal(uint64_t code) {
     auto solution = cache.front();
 
     while (solution != nullptr) {
+//        printf("%016lX\n", solution->code);
 //        std::cout << RawCode(solution->code).dump_case() << std::endl;
         solution = solution->last;
     }
diff --git a/src/main.cc b/src/main.cc
index 52d0567..86f183a 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -202,6 +202,7 @@ int main() {
 
     auto a = Analyse();
     a.start_analyse(raw_code);
+    a.backtrack(0x07F87E0E5BFFF492);
 
 //    int sum = 0;
 //    for (auto const &raw_code : all_cases_raw) {