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diff --git a/store/works/life/operating-system-challenge/.gitignore b/store/works/life/operating-system-challenge/.gitignore
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+*.exe
diff --git a/store/works/life/operating-system-challenge/1/README.md b/store/works/life/operating-system-challenge/1/README.md
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+> 挑战一：写一个程序，运行该进程时，你的电脑整体 CPU 利用率保持在 100%
+> 示例效果如
+> ![sample](sample.jpg)
+
+Transaltion: Write a program and make your CPU's usage rate 100%.
+
+Code is in `main.cpp`. Remember to not compile it with O2 optimization, or my dead loop will be eliminated.
+
+Final effect:
+![effect](effect.png)
diff --git a/store/works/life/operating-system-challenge/1/effect.png b/store/works/life/operating-system-challenge/1/effect.png
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index 0000000..b173ea0
--- /dev/null
+++ b/store/works/life/operating-system-challenge/1/effect.png
diff --git a/store/works/life/operating-system-challenge/1/main.cpp b/store/works/life/operating-system-challenge/1/main.cpp
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index 0000000..0f780ef
--- /dev/null
+++ b/store/works/life/operating-system-challenge/1/main.cpp
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+// Remember not to use O2 optimization!
+
+#include <thread>
+#include <vector>
+
+int main() {
+  std::vector<std::thread> threads;
+
+  // Because my CPU has 4-core and 8-threads. I open 8 threads.
+  for (int i = 0; i < 8; i++) {
+    std::thread t([] {
+      int i;
+      int j;
+      int k;
+      double d;
+      while (true) {
+        i = i + i;
+        j = j - j;
+        k = k * k;
+        d = d + d;
+        i = i & i;
+        j = j | j;
+      }
+    });
+    threads.push_back(std::move(t));
+  }
+
+  for (auto &t : threads) {
+    t.join();
+  }
+
+  return 0;
+}
diff --git a/store/works/life/operating-system-challenge/1/sample.jpg b/store/works/life/operating-system-challenge/1/sample.jpg
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index 0000000..7276bec
--- /dev/null
+++ b/store/works/life/operating-system-challenge/1/sample.jpg
diff --git a/store/works/life/operating-system-challenge/2/README.md b/store/works/life/operating-system-challenge/2/README.md
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index 0000000..86672f5
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+> 挑战二：写一个程序，运行该进程时，你计算机每一个核的 CPU 占用率是各不相同的有规律的曲线
+> 示例效果如：
+> ![sample](sample.jpg)
+
+Translation: Write a program and make each core of your CPU get a different but regular usage rate graph.
+
+Code is in `main.cpp`. Remember to not compile it with O2 optimization, or my loop will be eliminated.
+
+Final effect:
+![effect](effect.png)
diff --git a/store/works/life/operating-system-challenge/2/effect.png b/store/works/life/operating-system-challenge/2/effect.png
new file mode 100644
index 0000000..984a3da
--- /dev/null
+++ b/store/works/life/operating-system-challenge/2/effect.png
diff --git a/store/works/life/operating-system-challenge/2/main.cpp b/store/works/life/operating-system-challenge/2/main.cpp
new file mode 100644
index 0000000..a497442
--- /dev/null
+++ b/store/works/life/operating-system-challenge/2/main.cpp
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+#include <Windows.h>
+#include <cmath>
+
+DWORD WINAPI Thread1(_In_ LPVOID lpParameter) {
+  int i;
+  while (true) {
+    i++;
+  }
+  return 0;
+}
+
+DWORD WINAPI Thread2(_In_ LPVOID lpParameter) {
+  while (true) {
+    for (long long i = 0; i < 5000000000; i++)
+      ;
+    Sleep(10000);
+  }
+
+  return 0;
+}
+
+DWORD WINAPI Thread3(_In_ LPVOID lpParameter) {
+  while (true) {
+    for (int i = 0; i < 4000000; i++)
+      ;
+    Sleep(10);
+  }
+
+  return 0;
+}
+
+DWORD WINAPI Thread4(_In_ LPVOID lpParameter) {
+  LARGE_INTEGER frequency;
+  QueryPerformanceFrequency(&frequency);
+
+  LARGE_INTEGER count;
+  QueryPerformanceCounter(&count);
+
+  double current_y = 0;
+
+  while (true) {
+    for (int i = 0; i < 3000000.0 * (1.0 + current_y); i++)
+      ;
+    Sleep(10 * (1 - current_y));
+
+    LARGE_INTEGER new_count;
+    QueryPerformanceCounter(&new_count);
+
+    auto s = (new_count.QuadPart - count.QuadPart) / frequency.QuadPart;
+    current_y = std::sin(s / 30.0 * 2 * 3.1415926535) * 0.6;
+  }
+
+  return 0;
+}
+
+int main() {
+  HANDLE thread1 = CreateThread(NULL, 0, Thread1, NULL, 0, NULL);
+  HANDLE thread2 = CreateThread(NULL, 0, Thread2, NULL, 0, NULL);
+  HANDLE thread3 = CreateThread(NULL, 0, Thread3, NULL, 0, NULL);
+  HANDLE thread4 = CreateThread(NULL, 0, Thread4, NULL, 0, NULL);
+
+  SetThreadAffinityMask(thread1, 1);
+  SetThreadAffinityMask(thread2, 1 << 1);
+  SetThreadAffinityMask(thread3, 1 << 2);
+  SetThreadAffinityMask(thread4, 1 << 3);
+
+  WaitForSingleObject(thread1, INFINITE);
+  WaitForSingleObject(thread2, INFINITE);
+  WaitForSingleObject(thread3, INFINITE);
+  WaitForSingleObject(thread4, INFINITE);
+
+  return 0;
+}
diff --git a/store/works/life/operating-system-challenge/2/sample.jpg b/store/works/life/operating-system-challenge/2/sample.jpg
new file mode 100644
index 0000000..53b9f89
--- /dev/null
+++ b/store/works/life/operating-system-challenge/2/sample.jpg
diff --git a/store/works/life/operating-system-challenge/3/README.md b/store/works/life/operating-system-challenge/3/README.md
new file mode 100644
index 0000000..63fa023
--- /dev/null
+++ b/store/works/life/operating-system-challenge/3/README.md
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+![problem](problem.jpg)
+
+Translation: Use a lock to achieve that 3 threads print A, B, C in turn for 10 times. Output is `ABCABC...`
+
+Code is in `main.cpp`.
diff --git a/store/works/life/operating-system-challenge/3/main.cpp b/store/works/life/operating-system-challenge/3/main.cpp
new file mode 100644
index 0000000..461c775
--- /dev/null
+++ b/store/works/life/operating-system-challenge/3/main.cpp
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+#include <iostream>
+#include <mutex>
+#include <thread>
+
+int main() {
+  int turn = 1;
+  int count = 0;
+  std::mutex mutex;
+
+  auto thread_proc1 = [&] {
+    while (true) {
+      {
+        std::lock_guard<std::mutex> guard(mutex);
+        if (count >= 10)
+          break;
+        if (turn == 1) {
+          std::cout << "A" << std::endl;
+          turn = 2;
+        }
+      }
+
+      std::this_thread::yield();
+    }
+  };
+
+  auto thread_proc2 = [&] {
+    while (true) {
+      {
+        std::lock_guard<std::mutex> guard(mutex);
+        if (count >= 10)
+          break;
+        if (turn == 2) {
+          std::cout << "B" << std::endl;
+          turn = 3;
+        }
+      }
+
+      std::this_thread::yield();
+    }
+  };
+
+  auto thread_proc3 = [&] {
+    while (true) {
+      {
+        std::lock_guard<std::mutex> guard(mutex);
+        if (count >= 10)
+          break;
+        if (turn == 3) {
+          std::cout << "C" << std::endl;
+          turn = 1;
+          count++;
+        }
+      }
+
+      std::this_thread::yield();
+    }
+  };
+
+  std::thread thread1(thread_proc1);
+  std::thread thread2(thread_proc2);
+  std::thread thread3(thread_proc3);
+
+  thread1.join();
+  thread2.join();
+  thread3.join();
+
+  return 0;
+}
diff --git a/store/works/life/operating-system-challenge/3/problem.jpg b/store/works/life/operating-system-challenge/3/problem.jpg
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index 0000000..c3a61b7
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+++ b/store/works/life/operating-system-challenge/3/problem.jpg
diff --git a/store/works/life/operating-system-challenge/README.md b/store/works/life/operating-system-challenge/README.md
new file mode 100644
index 0000000..8a5898d
--- /dev/null
+++ b/store/works/life/operating-system-challenge/README.md
@@ -0,0 +1 @@
+Some challenges raised by my Operating System teacher, aka. Li Hao.