diff --git a/src/contests/contest30/SubarraySumEqualsK_JunitTest.java b/src/contests/contest30/SubarraySumEqualsK_JunitTest.java
new file mode 100644
index 0000000..c01fb23
--- /dev/null
+++ b/src/contests/contest30/SubarraySumEqualsK_JunitTest.java
@@ -0,0 +1,73 @@
+package contests.contest30;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class SubarraySumEqualsK_JunitTest {
+
+	@Test
+	void test0() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {1};
+		int result = SSEK.subarraySum(arr, 1);
+		assertEquals(1, result);
+	}
+	
+	@Test
+	void test1() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {};
+		int result = SSEK.subarraySum(arr, 8);
+		assertEquals(0, result);
+	}
+	
+	@Test
+	void test2() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {1,2,1};
+		int result = SSEK.subarraySum(arr, 1);
+		assertEquals(2, result);
+	}
+	
+	@Test
+	void test3() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {1,2,3,4,5};
+		int result = SSEK.subarraySum(arr, 0);
+		assertEquals(0, result);
+	}
+
+	@Test
+	void test4() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {1,2,1};
+		int result = SSEK.subarraySum(arr, 3);
+		assertEquals(2, result);
+	}
+	
+	@Test
+	void test5() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {1,-1,2,-2,-3,3};
+		int result = SSEK.subarraySum(arr, 0);
+		assertEquals(6, result);
+	}
+
+	@Test
+	void test6() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {-15,6,-3,-8,0,1,4,1,-2,4,3,-5,4};
+		int result = SSEK.subarraySum(arr, 0);
+		assertEquals(5, result);
+	}
+
+	@Test
+	void test7() {
+		SubarraySumEqualsK SSEK = new SubarraySumEqualsK();
+		int [] arr = {-3,4,12,6,2,-5,-3,0,5,-8,5,6,9};
+		int result = SSEK.subarraySum(arr, 8);
+		assertEquals(4, result);
+	}
+
+}
diff --git a/src/problems/medium/GasStation_Test.java b/src/problems/medium/GasStation_Test.java
new file mode 100644
index 0000000..c2b81b3
--- /dev/null
+++ b/src/problems/medium/GasStation_Test.java
@@ -0,0 +1,42 @@
+package problems.medium;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class GasStation_Test {
+	int [] a = {1,2,3,4,5};
+	int [] b = {2,3,4,5,6};
+	int [] c = {2,3,2,1,2};
+	int [] d = {2,1,5,1,2};
+	int [] e = {2,1,3,5,4};
+	
+	@Test
+	void test0() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,b);
+		assertEquals(-1, result);
+	}
+	
+	@Test
+	void test1() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,c);
+		assertEquals(2, result);
+	}
+	
+	@Test
+	void test2() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,d);
+		assertEquals(3, result);
+	}
+	
+	@Test
+	void test3() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,e);
+		assertEquals(1, result);
+	}
+
+}
diff --git a/src/problems/medium/GasStation_Test_All_DU_path.java b/src/problems/medium/GasStation_Test_All_DU_path.java
new file mode 100644
index 0000000..592b686
--- /dev/null
+++ b/src/problems/medium/GasStation_Test_All_DU_path.java
@@ -0,0 +1,55 @@
+package problems.medium;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class GasStation_Test_All_DU_path {
+	int [] a = {4,1,2,2,5};
+	int [] b = {2,5,3,4,3};
+	int [] c = {6,2,4,3,5};
+	int [] d = {5,2,1,2,3};
+	int [] e = {3,1,4,2,1};
+	int [] f = {4,1,3,1,4};
+	
+	@Test
+	// Kiểm thử All-DU path cho biến totgas
+	void test0() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,b);
+		assertEquals(-1, result);
+	}
+	
+	@Test
+	// Kiểm thử All-DU path cho biến totcost
+	void test1() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,c);
+		assertEquals(-1, result);
+	}
+	
+	@Test
+	// Kiểm thử All-DU path cho biến current
+	void test2() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,d);
+		assertEquals(2, result);
+	}
+	
+	@Test
+	// Kiểm thử All-DU path cho biến current
+	void test3() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,e);
+		assertEquals(3, result);
+	}
+
+	@Test
+	// Kiểm thử All-DU path cho biến k
+	void test4() {
+		GasStation gs = new GasStation();
+		int result = gs.canCompleteCircuit(a,f);
+		assertEquals(3, result);
+	}
+
+}