Add MinSumKSizeSubarray algorithm (#6025)

src/test/java/com/thealgorithms/slidingwindow/MinSumKSizeSubarrayTest.java

@@ -0,0 +1,79 @@
+package com.thealgorithms.slidingwindow;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the MinSumKSizeSubarray class.
+ *
+ * @author Rashi Dashore (https://github.com/rashi07dashore)
+ */
+class MinSumKSizeSubarrayTest {
+
+    /**
+     * Test for the basic case of finding the minimum sum.
+     */
+    @Test
+    void testMinSumKSizeSubarray() {
+        int[] arr = {2, 1, 5, 1, 3, 2};
+        int k = 3;
+        int expectedMinSum = 6; // Corrected: Minimum sum of a subarray of size 3
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+
+    /**
+     * Test for a different array and subarray size.
+     */
+    @Test
+    void testMinSumKSizeSubarrayWithDifferentValues() {
+        int[] arr = {1, 2, 3, 4, 5};
+        int k = 2;
+        int expectedMinSum = 3; // 1 + 2
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+
+    /**
+     * Test for edge case with insufficient elements.
+     */
+    @Test
+    void testMinSumKSizeSubarrayWithInsufficientElements() {
+        int[] arr = {1, 2};
+        int k = 3; // Not enough elements
+        int expectedMinSum = -1; // Edge case
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+
+    /**
+     * Test for large array.
+     */
+    @Test
+    void testMinSumKSizeSubarrayWithLargeArray() {
+        int[] arr = {5, 4, 3, 2, 1, 0, -1, -2, -3, -4};
+        int k = 5;
+        int expectedMinSum = -10; // -1 + -2 + -3 + -4 + 0
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+
+    /**
+     * Test for array with negative numbers.
+     */
+    @Test
+    void testMinSumKSizeSubarrayWithNegativeNumbers() {
+        int[] arr = {-1, -2, -3, -4, -5};
+        int k = 2;
+        int expectedMinSum = -9; // -4 + -5
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+
+    /**
+     * Test for the case where k equals the array length.
+     */
+    @Test
+    void testMinSumKSizeSubarrayWithKEqualToArrayLength() {
+        int[] arr = {1, 2, 3, 4, 5};
+        int k = 5;
+        int expectedMinSum = 15; // 1 + 2 + 3 + 4 + 5
+        assertEquals(expectedMinSum, MinSumKSizeSubarray.minSumKSizeSubarray(arr, k));
+    }
+}