diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 72d924d..4013eb9 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -6,4 +6,4 @@ project(klotski-core VERSION 0.1.2 LANGUAGES CXX)
 
 add_compile_options(-fno-exceptions)
 
-add_executable(${PROJECT_NAME} main.cc all_cases/basic_ranges.cc)
+add_executable(${PROJECT_NAME} main.cc all_cases/basic_ranges.cc all_cases/all_cases.cc)
diff --git a/src/core/all_cases/all_cases.cc b/src/core/all_cases/all_cases.cc
new file mode 100644
index 0000000..089f0d5
--- /dev/null
+++ b/src/core/all_cases/all_cases.cc
@@ -0,0 +1,139 @@
+#include <iostream>
+
+#include "reverse.h"
+#include "all_cases.h"
+
+//typedef uint32_t Range;
+
+using klotski::cases::BasicRanges;
+using klotski::cases::range_reverse;
+
+uint32_t check_range(uint32_t head, uint32_t range) noexcept {
+    ///   M_1x1   |   M_1x2   |   M_2x1   |   M_2x2
+    ///  1 0 0 0  |  1 1 0 0  |  1 0 0 0  |  1 1 0 0
+    ///  0 0 0 0  |  0 0 0 0  |  1 0 0 0  |  1 1 0 0
+    ///  ...      |  ...      |  ...      |  ...
+    constexpr uint32_t M_1x1 = 0b1;
+    constexpr uint32_t M_1x2 = 0b11;
+    constexpr uint32_t M_2x1 = 0b10001;
+    constexpr uint32_t M_2x2 = 0b110011;
+
+    uint32_t offset = 1;
+    uint32_t tmp = M_2x2 << head; // fill 2x2 block
+    for (int addr = 0; range; range >>= 2, ++offset) { // traverse every 2-bits
+        while ((tmp >> addr) & 0b1) {
+            ++addr; // search next unfilled block
+        }
+        switch (range & 0b11) {
+            case 0b00: /// space
+            case 0b11: /// 1x1 block
+                tmp |= M_1x1 << addr; // fill space or 1x1 block
+                break;
+            case 0b10: /// 2x1 block
+                if (addr > 15 || tmp >> (addr + 4) & 0b1) { // invalid address
+                    return offset; // broken block number
+                }
+                tmp |= M_2x1 << addr; // fill 2x1 block
+                break;
+            case 0b01: /// 1x2 block
+                if ((addr & 0b11) == 0b11 || tmp >> (addr + 1) & 0b1) { // invalid address
+                    return offset; // broken block number
+                }
+                tmp |= M_1x2 << addr; // fill 1x2 block
+                break;
+        }
+    }
+    return 0; // pass check
+}
+
+int check_range_v2(int head, uint32_t range) noexcept {
+    constexpr uint32_t MASK_1x1 = 0b00000001;
+    constexpr uint32_t MASK_1x2 = 0b00000011;
+    constexpr uint32_t MASK_2x1 = 0b00010001;
+    constexpr uint32_t MASK_2x2 = 0b00110011;
+
+    uint32_t flags = MASK_2x2 << head;
+
+    for (int addr = 0; range; range >>= 2) {
+
+        int nn = __builtin_ctz(~flags);
+        addr += nn;
+        flags >>= nn;
+
+        switch (range & 0b11) {
+            case 0b00:
+            case 0b11:
+                flags |= MASK_1x1;
+                continue;
+            case 0b10:
+                if ((flags >> 4) & 0b1 || addr > 15) { // invalid address
+                    return -1; // broken block number
+                }
+                flags |= MASK_2x1;
+                continue;
+            case 0b01:
+                if ((flags >> 1) & 0b1 || (addr & 0b11) == 0b11) { // invalid address
+                    return -1; // broken block number
+                }
+                flags |= MASK_1x2;
+                continue;
+        }
+    }
+
+    return 0;
+}
+
+void demo() {
+
+//    std::cout << check_range(1, 0x003F78CE) << std::endl;
+//    std::cout << check_range_v3(1, 0x003F78CE) << std::endl;
+//    return;
+
+//    uint32_t demo = 0x61;
+//    std::cout << __builtin_ctz(demo) << std::endl;
+//    return;
+
+    // 0xA9BF0C00
+//    auto ret = check_range_v2(1, range_reverse(0xA9BF0C00));
+//    std::cout << ret << std::endl;
+//    return;
+//    std::cout << ret << std::endl;
+
+    constexpr std::array<int, 12> heads = {
+        0x0, 0x1, 0x2,
+        0x4, 0x5, 0x6,
+        0x8, 0x9, 0xA,
+        0xC, 0xD, 0xE,
+    };
+
+    auto num = 0;
+    for (auto head : heads) {
+        for (auto x : BasicRanges::Instance().Fetch()) {
+            if (check_range_v2(head, x) == 0) {
+                ++num;
+            }
+        }
+    }
+
+
+//    auto basic_ranges = BasicRanges::Instance().Fetch();
+//    for (auto head : heads) {
+//        for (uint32_t index = 0; index < basic_ranges.size(); ++index) {
+//            auto broken_offset = check_range(head, basic_ranges[index]);
+//            if (broken_offset) { // case invalid
+//                auto delta = (uint32_t)1 << (32 - broken_offset * 2); // delta to next possible range
+//                ///         !! -> broken
+//                /// ( xx xx xx ) xx xx xx ... (reversed range)
+//                ///         +1   00 00 00 ... (delta)
+//                auto at_least = (range_reverse(basic_ranges[index]) & ~(delta - 1)) + delta;
+//                while (range_reverse(basic_ranges[++index]) < at_least); // located next range
+//                --index;
+//                continue;
+//            }
+//            volatile auto r = range_reverse(basic_ranges[index]); // release valid cases
+//        }
+//    }
+
+//    std::cout << num << std::endl;
+
+}
diff --git a/src/core/all_cases/all_cases.h b/src/core/all_cases/all_cases.h
index 795d22b..69700f4 100644
--- a/src/core/all_cases/all_cases.h
+++ b/src/core/all_cases/all_cases.h
@@ -39,6 +39,8 @@
 #include <vector>
 #include <cstdint>
 
+void demo();
+
 namespace klotski {
 namespace cases {
 
diff --git a/src/core/main.cc b/src/core/main.cc
index c3a5b52..679d69b 100644
--- a/src/core/main.cc
+++ b/src/core/main.cc
@@ -5,14 +5,19 @@
 using klotski::cases::BasicRanges;
 
 int main() {
+
+    BasicRanges::Instance().Build();
+
     auto start = clock();
 
+    demo();
+
 //    std::cout << BasicRanges::Instance().IsAvailable() << std::endl;
 //    BasicRanges::Instance().Build();
 //    std::cout << BasicRanges::Instance().IsAvailable() << std::endl;
-    for (auto x : BasicRanges::Instance().Fetch()) {
-        printf("%08X\n", x);
-    }
+//    for (auto x : BasicRanges::Instance().Fetch()) {
+//        printf("%08X\n", x);
+//    }
 
     std::cerr << ((clock() - start) * 1000 / CLOCKS_PER_SEC) << "ms" << std::endl;