Add ReverseWordsInString (#4456)

* return a string of the words in reverse order concatenated by a single space.

Input: s = "the sky is blue"
Output: "blue is sky the"

* return a string of the words in reverse order concatenated by a single space.

Input: s = "the sky is blue"
Output: "blue is sky the"

* space reduce

* removed main method

* added test cases

* formatting fix

* formatting fix

* worked on pr reviews

* formatting fix

* private constructor added

* added test case for when string contains white space

* simplified method

* fix issue

* formatting issues fix

* fixed issue

* code refactor

* documented method

* worked on pr comments

* docs: add missing space

* tests: express as `ParameterizedTest`

---------

Co-authored-by: Piotr Idzik <65706193+vil02@users.noreply.github.com>
Co-authored-by: vil02 <vil02@o2.pl>

src/main/java/com/thealgorithms/strings/ReverseWordsInString.java

@@ -0,0 +1,22 @@
+package com.thealgorithms.strings;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+public final class ReverseWordsInString {
+
+    private ReverseWordsInString() {
+    }
+
+    /**
+     * @brief Reverses words in the input string
+     * @param s the input string
+     * @return A string created by reversing the order of the words in {@code s}
+     */
+
+    public static String reverseWordsInString(final String s) {
+        var words = s.trim().split("\\s+");
+        Collections.reverse(Arrays.asList(words));
+        return String.join(" ", words);
+    }
+}

src/test/java/com/thealgorithms/strings/ReverseWordsInStringTest.java

@@ -0,0 +1,20 @@
+package com.thealgorithms.strings;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class ReverseWordsInStringTest {
+    @ParameterizedTest
+    @MethodSource("inputStream")
+    void numberTests(String expected, String input) {
+        Assertions.assertEquals(expected, ReverseWordsInString.reverseWordsInString(input));
+    }
+
+    private static Stream<Arguments> inputStream() {
+        return Stream.of(Arguments.of("blue is Sky", "Sky is blue"), Arguments.of("blue is Sky", "Sky \n is \t \n  blue "), Arguments.of("", ""), Arguments.of("", "    "), Arguments.of("", "\t"));
+    }
+}