diff --git a/20240906/bitset.cpp b/20240906/bitset.cpp
new file mode 100644
index 0000000..fa319de
--- /dev/null
+++ b/20240906/bitset.cpp
@@ -0,0 +1,52 @@
+#include <array>
+#include <climits>
+#include <cstddef>
+#include <format>
+#include <iostream>
+#include <vector>
+using namespace std;
+
+typedef unsigned int u8;
+typedef int i8;
+
+const u8 MAX = 1e5+1;
+
+constexpr std::array<u8, (size_t)MAX> initLog2(){
+    std::array<u8, (size_t)MAX> log2{};
+    log2[1]=0;
+    for(int i=2;i<=(int)MAX-1;i++){
+        log2[i]=log2[i/2]+1;
+    }
+    return log2;
+}
+
+class BitIntSet{
+private:
+    constexpr static const std::array<u8, (size_t)MAX> log2=initLog2();
+public:
+    i8 data;
+    
+    explicit BitIntSet(i8 n):data{n}{
+        // checkLog2IsInitalized();
+    }
+    int getLowbit()const{
+        return this->data&((~this->data)+1);
+    }
+    int getLowbit(u8 n)const{
+        return n&((~n)+1);
+    }
+    std::vector<u8> get1Dir()const{
+        std::vector<u8> ret;
+        int temp=this->data;
+        while(temp>0){
+            ret.push_back(log2[this->getLowbit()]);
+            temp-=getLowbit(temp);
+        }
+        return ret;
+    }
+};
+
+int main(){
+    BitIntSet b(10);
+    std::cout<<std::format("{0}.getLowbit()={1}\n{0}.get1Dir()={2}",b.data,b.getLowbit(),b.getLowbit());
+}
\ No newline at end of file
diff --git a/test.cpp b/test.cpp
new file mode 100644
index 0000000..ff8d8de
--- /dev/null
+++ b/test.cpp
@@ -0,0 +1,10 @@
+#include <iostream>
+using namespace std;
+
+
+
+int main(){
+    unsigned int a{};
+    for(;;){a++;}
+    cout<<a<<endl;
+}
\ No newline at end of file
diff --git a/xmake.lua b/xmake.lua
index 433a45f..c89966a 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -5,8 +5,10 @@ if is_mode("debug") then
 end 
 if is_mode("release") then 
     add_cxxflags("-march=native")
+    add_cxxflags("-fconstexpr-loop-limit=2147483647")
+    add_cxxflags("-fconstexpr-ops-limit=2147483647")
 end 
-set_languages("c++17")
+set_languages("c++23")
 set_warnings("all")
 
 target("P1158")
@@ -38,4 +40,10 @@ target("P2661")
     add_files("20240830/P2661/P2661.cpp")
 
 target("6261")
-    add_files("20240901/6261/6261.cpp")
\ No newline at end of file
+    add_files("20240901/6261/6261.cpp")
+
+target("test")
+    add_files("test.cpp")
+
+target("bitset")
+    add_files("20240906/bitset.cpp")
\ No newline at end of file