Add RandomizedClosestPair Algorithm and Unit Tests (#6339)

src/test/java/com/thealgorithms/randomized/RandomizedClosestPairTest.java

@@ -0,0 +1,30 @@
+package com.thealgorithms.randomized;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.thealgorithms.randomized.RandomizedClosestPair.Point;
+import org.junit.jupiter.api.Test;
+
+public class RandomizedClosestPairTest {
+
+    @Test
+    public void testFindClosestPairDistance() {
+        Point[] points = {new Point(1, 1), new Point(2, 2), new Point(3, 3), new Point(8, 8), new Point(13, 13)};
+        double result = RandomizedClosestPair.findClosestPairDistance(points);
+        assertEquals(Math.sqrt(2), result, 0.00001);
+    }
+
+    @Test
+    public void testWithIdenticalPoints() {
+        Point[] points = {new Point(0, 0), new Point(0, 0), new Point(1, 1)};
+        double result = RandomizedClosestPair.findClosestPairDistance(points);
+        assertEquals(0.0, result, 0.00001);
+    }
+
+    @Test
+    public void testWithDistantPoints() {
+        Point[] points = {new Point(0, 0), new Point(5, 0), new Point(10, 0)};
+        double result = RandomizedClosestPair.findClosestPairDistance(points);
+        assertEquals(5.0, result, 0.00001);
+    }
+}