diff --git a/include/solution/326.h b/include/solution/326.h
new file mode 100644
index 0000000..c53853c
--- /dev/null
+++ b/include/solution/326.h
@@ -0,0 +1,12 @@
+#ifndef INC_326_H
+#define INC_326_H
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+#include <stdbool.h>
+    bool isPowerOfThree(int n);
+#ifdef __cplusplus
+}
+#endif
+#endif
diff --git a/src/326.c b/src/326.c
new file mode 100644
index 0000000..7a80d1a
--- /dev/null
+++ b/src/326.c
@@ -0,0 +1,23 @@
+#define METHOD 2
+#include <solution/326.h>
+
+bool isPowerOfThree(int n)
+{
+#if METHOD == 1
+    if (n <= 0)
+        return false;
+
+    while (n != 1)
+    {
+        if (n % 3 != 0)
+            return false;
+        n /= 3;
+    }
+
+    return true;
+#elif METHOD == 2
+    // 在题目给定的 32 位有符号整数的范围内，最大的 3 的幂为 3^19 = 1162261467。
+    // 我们只需要判断 n 是否是 3^19 的约数即可。
+    return n > 0 && 1162261467 % n == 0;
+#endif
+}
\ No newline at end of file
diff --git a/tests/test_326.cpp b/tests/test_326.cpp
new file mode 100644
index 0000000..008cc8b
--- /dev/null
+++ b/tests/test_326.cpp
@@ -0,0 +1,34 @@
+#include <gtest/gtest.h>
+#include <solution/326.h>
+
+class IsPowerOfThreeTest : public ::testing::Test
+{
+  protected:
+    void AssertIsPowerOfThree(int input, bool expected)
+    {
+        EXPECT_EQ(isPowerOfThree(input), expected);
+    }
+};
+
+// 示例测试用例
+TEST_F(IsPowerOfThreeTest, ExampleTrueCases)
+{
+    AssertIsPowerOfThree(27, true);
+    AssertIsPowerOfThree(9, true);
+    AssertIsPowerOfThree(1, true); // 3^0 = 1
+    AssertIsPowerOfThree(3, true);
+}
+
+TEST_F(IsPowerOfThreeTest, ExampleFalseCases)
+{
+    AssertIsPowerOfThree(0, false);
+    AssertIsPowerOfThree(45, false);
+    AssertIsPowerOfThree(-3, false);
+    AssertIsPowerOfThree(10, false);
+}
+
+TEST_F(IsPowerOfThreeTest, EdgeCases)
+{
+    AssertIsPowerOfThree(INT_MIN, false);
+    AssertIsPowerOfThree(INT_MAX, false); // INT_MAX = 2^31 - 1，不是3的幂
+}
\ No newline at end of file