Add RangeSumQuery algorithm in prefix folder (#7280)

* add Subarray Sum Equals K using prefix sum

* Add RangeSumQuery algorithm in prefix folder

* chore: apply clang-format to RangeSumQueryTest file

* Add import statement for JUnit test class

---------

Co-authored-by: Deniz Altunkapan <deniz.altunkapan@outlook.com>

src/test/java/com/thealgorithms/prefixsum/RangeSumQueryTest.java

@@ -0,0 +1,73 @@
+package com.thealgorithms.prefixsum;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for {@link RangeSumQuery}.
+ */
+class RangeSumQueryTest {
+
+    @Test
+    void testBasicExample() {
+        int[] nums = {1, 2, 3, 4, 5};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertEquals(6, RangeSumQuery.sumRange(prefixSum, 0, 2)); // 1+2+3
+        assertEquals(9, RangeSumQuery.sumRange(prefixSum, 1, 3)); // 2+3+4
+        assertEquals(15, RangeSumQuery.sumRange(prefixSum, 0, 4)); // 1+2+3+4+5
+        assertEquals(12, RangeSumQuery.sumRange(prefixSum, 2, 4)); // 3+4+5
+    }
+
+    @Test
+    void testSingleElement() {
+        int[] nums = {7};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertEquals(7, RangeSumQuery.sumRange(prefixSum, 0, 0));
+    }
+
+    @Test
+    void testAllZeros() {
+        int[] nums = {0, 0, 0, 0};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertEquals(0, RangeSumQuery.sumRange(prefixSum, 0, 3));
+        assertEquals(0, RangeSumQuery.sumRange(prefixSum, 1, 2));
+    }
+
+    @Test
+    void testNegativeNumbers() {
+        int[] nums = {-1, 2, -3, 4};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertEquals(-2, RangeSumQuery.sumRange(prefixSum, 0, 2)); // -1+2-3
+        assertEquals(3, RangeSumQuery.sumRange(prefixSum, 1, 3)); // 2-3+4
+    }
+
+    @Test
+    void testEmptyArrayThrowsException() {
+        int[] nums = {};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 0, 0));
+    }
+
+    @Test
+    void testNullArrayThrowsException() {
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.buildPrefixSum(null));
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(null, 0, 0));
+    }
+
+    @Test
+    void testInvalidIndicesThrowsException() {
+        int[] nums = {1, 2, 3};
+        int[] prefixSum = RangeSumQuery.buildPrefixSum(nums);
+
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, -1, 2));
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 1, 5));
+        assertThrows(IllegalArgumentException.class, () -> RangeSumQuery.sumRange(prefixSum, 2, 1));
+    }
+}