diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index a1b014f..4c32ed7 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -13,6 +13,8 @@ include_directories(core)
 include_directories(analyse)
 include_directories(fast_cal)
 
+include_directories(graph)
+
 ################################################
 
 add_subdirectory(utils)
@@ -26,6 +28,8 @@ add_subdirectory(core)
 add_subdirectory(analyse)
 add_subdirectory(fast_cal)
 
+add_subdirectory(graph)
+
 ################################################
 
 add_executable(klotski main.cc)
@@ -43,6 +47,8 @@ target_link_libraries(klotski core)
 target_link_libraries(klotski analyse)
 target_link_libraries(klotski fast_cal)
 
+target_link_libraries(klotski graph)
+
 target_link_libraries(klotski pthread)
 
 ################################################
diff --git a/src/analyse/analyse.h b/src/analyse/analyse.h
index f8a330d..3888962 100644
--- a/src/analyse/analyse.h
+++ b/src/analyse/analyse.h
@@ -45,15 +45,15 @@ private:
 
 /// backtrack definitions
 public:
-    struct backtrack_t {
+    struct track_t {
         uint64_t code;
         uint32_t layer_num;
-        std::list<backtrack_t*> last;
-        std::list<backtrack_t*> next;
+        std::list<track_t*> last;
+        std::list<track_t*> next;
     };
-    typedef std::vector<std::unordered_map<uint64_t, backtrack_t>> backtrack_data_t;
+    typedef std::vector<std::unordered_map<uint64_t, track_t>> track_data_t;
 
     // TODO: try using unordered_set
-    backtrack_data_t backtrack_demo(const std::vector<uint64_t> &codes);
+    track_data_t backtrack(const std::vector<uint64_t> &codes);
 
 };
diff --git a/src/analyse/backtrack.cc b/src/analyse/backtrack.cc
index 1e88fd7..a755696 100644
--- a/src/analyse/backtrack.cc
+++ b/src/analyse/backtrack.cc
@@ -1,15 +1,13 @@
 #include <algorithm>
 #include "analyse.h"
 
-#include <iostream>
-
-Analyse::backtrack_data_t Analyse::backtrack_demo(const std::vector<uint64_t> &codes) {
+Analyse::track_data_t Analyse::backtrack(const std::vector<uint64_t> &codes) {
     /// codes pre-check and sort by steps
     std::vector<std::vector<analyse_t*>> todos;
     for (const auto &code : codes) {
         auto c = cases.find(code);
         if (c == cases.end()) { // invalid input
-            return backtrack_data_t{}; // return empty data
+            return track_data_t{}; // return empty data
         }
         if (c->second.step >= todos.size()) {
             todos.resize(c->second.step + 1); // enlarge schedule list
@@ -20,10 +18,10 @@ Analyse::backtrack_data_t Analyse::backtrack_demo(const std::vector<uint64_t> &c
 
     struct cache_t {
         analyse_t *a;
-        backtrack_t *b;
+        track_t *b;
     };
     std::queue<cache_t> track_cache;
-    Analyse::backtrack_data_t track_data(todos.size());
+    track_data_t track_data(todos.size());
     /// start backtrack process
     for (const auto &todo : todos) {
         if (todo.empty()) {
@@ -35,11 +33,11 @@ Analyse::backtrack_data_t Analyse::backtrack_demo(const std::vector<uint64_t> &c
             if (track_data[c->step].find(c->code) == track_data[c->step].end()) {
                 track_cache.emplace(cache_t{
                     .a = c,
-                    .b = &track_data[c->step].emplace(c->code, backtrack_t{
+                    .b = &track_data[c->step].emplace(c->code, track_t{
                         .code = c->code,
                         .layer_num = c->step,
-                        .last = std::list<backtrack_t *>{}, // without parent node
-                        .next = std::list<backtrack_t *>{}, // without sub node
+                        .last = std::list<track_t*>{}, // without parent node
+                        .next = std::list<track_t*>{}, // without sub node
                     }).first->second,
                 });
             }
@@ -55,11 +53,11 @@ Analyse::backtrack_data_t Analyse::backtrack_demo(const std::vector<uint64_t> &c
                     curr.b->last.emplace_back(&t_src->second);
                 } else { // src case not found
                     /// link (curr.b) and (t_src_new->second)
-                    auto t_src_new = track_data[src->step].emplace(src->code, backtrack_t {
+                    auto t_src_new = track_data[src->step].emplace(src->code, track_t {
                         .code = src->code,
                         .layer_num = src->step,
-                        .last = std::list<backtrack_t*>{},
-                        .next = std::list<backtrack_t*>{curr.b}, // link to curr.b
+                        .last = std::list<track_t*>{},
+                        .next = std::list<track_t*>{curr.b}, // link to curr.b
                     }).first;
                     curr.b->last.emplace_back(&t_src_new->second);
                     /// insert into working queue
@@ -72,32 +70,5 @@ Analyse::backtrack_data_t Analyse::backtrack_demo(const std::vector<uint64_t> &c
             track_cache.pop();
         }
     }
-
-
-
-    for (uint32_t i = 0; i < track_data.size(); ++i) {
-
-        const auto &ly = track_data[i];
-
-        std::cout << std::endl;
-        std::cout << "----------------------------------";
-        std::cout << " layer " << i << " ";
-        std::cout << "----------------------------------" << std::endl;
-
-        for (const auto &c : ly) {
-            for (const auto &l : c.second.last) {
-                std::cout << l->code << " ";
-            }
-            std::cout << " <- [" << c.second.code << "] -> ";
-            for (const auto &n : c.second.next) {
-                std::cout << n->code << " ";
-            }
-            std::cout << std::endl;
-        }
-
-    }
-
-
     return track_data;
-
 }
diff --git a/src/graph/CMakeLists.txt b/src/graph/CMakeLists.txt
new file mode 100644
index 0000000..df15942
--- /dev/null
+++ b/src/graph/CMakeLists.txt
@@ -0,0 +1,4 @@
+cmake_minimum_required(VERSION 3.0)
+
+add_library(graph graph.cc)
+target_link_libraries(graph analyse)
diff --git a/src/graph/graph.cc b/src/graph/graph.cc
new file mode 100644
index 0000000..e29c0cd
--- /dev/null
+++ b/src/graph/graph.cc
@@ -0,0 +1,30 @@
+#include "graph.h"
+
+#include <iostream>
+
+void Graph::svg_demo(Analyse::track_data_t track_data) {
+
+
+    for (uint32_t i = 0; i < track_data.size(); ++i) {
+
+        const auto &ly = track_data[i];
+
+        std::cout << std::endl;
+        std::cout << "----------------------------------";
+        std::cout << " layer " << i << " ";
+        std::cout << "----------------------------------" << std::endl;
+
+        for (const auto &c : ly) {
+            for (const auto &l : c.second.last) {
+                std::cout << l->code << " ";
+            }
+            std::cout << " <- [" << c.second.code << "] -> ";
+            for (const auto &n : c.second.next) {
+                std::cout << n->code << " ";
+            }
+            std::cout << std::endl;
+        }
+
+    }
+
+}
diff --git a/src/graph/graph.h b/src/graph/graph.h
new file mode 100644
index 0000000..7aeb3fa
--- /dev/null
+++ b/src/graph/graph.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include "analyse.h"
+
+class Graph {
+
+public:
+
+    void svg_demo(Analyse::track_data_t track_data);
+
+};
diff --git a/src/main.cc b/src/main.cc
index ebb6d43..2048c39 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -8,6 +8,7 @@
 #include "fast_cal.h"
 #include "analyse.h"
 #include "common.h"
+#include "graph.h"
 
 #include <thread>
 #include <algorithm>
@@ -65,14 +66,11 @@ int main() {
 //        std::cout << r << std::endl;
 //    }
 
-    std::vector<uint64_t> dat = {
+    auto ret = a.backtrack({
         0x7F87E0E5BFFF492, 0x1FB1E36F9FFF492
-    };
-
-//    a.backtrack_demo(0x7F87E0E5BFFF492);
-//    a.backtrack_demo(0x1FB1E36F9FFF492);
-
-    a.backtrack_demo(dat);
+    });
+    auto g = Graph();
+    g.svg_demo(ret);
 
 //    auto start_time = clock();