Add unique paths (fixes #2873) (#2943)

Co-authored-by: Andrii Siriak <siryaka@gmail.com>

src/test/java/com/thealgorithms/others/UniquePathsTests.java

@@ -0,0 +1,56 @@
+package com.thealgorithms.others;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.thealgorithms.dynamicprogramming.UniquePaths;
+
+
+public class UniquePathsTests {
+    @Test
+	void testForOneElement() 
+	{
+		assertTrue(UniquePaths.uniquePaths(3,7,28));
+	}
+
+	@Test
+	void testForTwoElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths(3,2,3));
+	}
+
+	@Test
+	void testForThreeElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths(3,3,6));
+	}
+
+	@Test
+	void testForFourElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths(4,6,56));
+	}
+
+	@Test
+	void testForFiveElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths2(3,5,15));
+	}
+
+	@Test
+	void testForSixElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths2(6,2,6));
+	}
+
+	@Test
+	void testForSevenElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths2(5,9,495));
+    }
+
+	@Test
+	void testForEightElements() 
+	{
+		assertTrue(UniquePaths.uniquePaths2(4,8,120));
+	}
+}