Add solution for the "Check If Two String Arrays are Equivalent" problem with unit tests.

src/main/java/com/leetcode/easy/CheckIfTwoStringArraysAreEquivalent1662.java

@@ -0,0 +1,13 @@
+// Tags: Array, String
+package com.leetcode.easy;
+
+public class CheckIfTwoStringArraysAreEquivalent1662 {
+    /*
+        Let N be the maximum of the number of all characters in word1 and the number of all characters in word2.
+        Time complexity: O(N), since we need to iterate over all characters in word1 and word2 to build the new strings.
+        Space complexity: O(N), since we need extra O(N) space to store the new built strings.
+     */
+    public boolean arrayStringsAreEqual(String[] word1, String[] word2) {
+        return String.join("", word1).equals(String.join("", word2));
+    }
+}

src/test/java/com/leetcode/easy/CheckIfTwoStringArraysAreEquivalent1662Test.java

@@ -0,0 +1,46 @@
+package com.leetcode.easy;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class CheckIfTwoStringArraysAreEquivalent1662Test {
+    private CheckIfTwoStringArraysAreEquivalent1662 solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new CheckIfTwoStringArraysAreEquivalent1662();
+    }
+
+    @Test
+    void testArrayStringsAreEqual_Example1() {
+        String[] word1 = {"ab", "c"};
+        String[] word2 = {"a", "bc"};
+
+        boolean result = solution.arrayStringsAreEqual(word1, word2);
+
+        assertTrue(result);
+    }
+
+    @Test
+    void testArrayStringsAreEqual_Example2() {
+        String[] word1 = {"a", "cb"};
+        String[] word2 = {"ab", "c"};
+
+        boolean result = solution.arrayStringsAreEqual(word1, word2);
+
+        assertFalse(result);
+    }
+
+    @Test
+    void testArrayStringsAreEqual_Example3() {
+        String[] word1 = {"abc", "d", "defg"};
+        String[] word2 = {"abcddefg"};
+
+        boolean result = solution.arrayStringsAreEqual(word1, word2);
+
+        assertTrue(result);
+    }
+}