test: add LeetCode 1929 with tests, complexity docs, and migration

README.md

@@ -44,11 +44,11 @@ Each problem follows this structure:
 
 ## Solutions
 
-📊 **Statistics**: 55 problems solved (migrated to new structure)
+📊 **Statistics**: 56 problems solved (migrated to new structure)
 
 | Difficulty | Count |
 |------------|-------|
-| Easy       | 39    |
+| Easy       | 40    |
 | Medium     | 15    |
 | Hard       | 1     |
 

docs/EASY.md

@@ -1,6 +1,6 @@
 # Easy Problems
 
-Total: 39 problems solved
+Total: 40 problems solved
 
 ## Solutions
 
@@ -35,6 +35,7 @@ Total: 39 problems solved
 | 1684 | [Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings/) | [CountTheNumberOfConsistentStrings1684.java](../src/main/java/com/leetcode/easy/CountTheNumberOfConsistentStrings1684.java) | [CountTheNumberOfConsistentStrings1684Test.java](../src/test/java/com/leetcode/easy/CountTheNumberOfConsistentStrings1684Test.java) |
 | 1773 | [Count Items Matching a Rule](https://leetcode.com/problems/count-items-matching-a-rule/) | [CountItemsMatchingARule1773.java](../src/main/java/com/leetcode/easy/CountItemsMatchingARule1773.java) | [CountItemsMatchingARule1773Test.java](../src/test/java/com/leetcode/easy/CountItemsMatchingARule1773Test.java) |
 | 1816 | [Truncate Sentence](https://leetcode.com/problems/truncate-sentence/) | [TruncateSentence1816.java](../src/main/java/com/leetcode/easy/TruncateSentence1816.java) | [TruncateSentence1816Test.java](../src/test/java/com/leetcode/easy/TruncateSentence1816Test.java) |
+| 1929 | [Concatenation of Array](https://leetcode.com/problems/concatenation-of-array/) | [ConcatenationOfArray1929.java](../src/main/java/com/leetcode/easy/ConcatenationOfArray1929.java) | [ConcatenationOfArray1929Test.java](../src/test/java/com/leetcode/easy/ConcatenationOfArray1929Test.java) |
 | 1941 | [Check if All Characters Have Equal Number of Occurrences](https://leetcode.com/problems/check-if-all-characters-have-equal-number-of-occurrences/) | [CheckIfAllCharactersHaveEqualNumberOfOccurrences1941.java](../src/main/java/com/leetcode/easy/CheckIfAllCharactersHaveEqualNumberOfOccurrences1941.java) | [CheckIfAllCharactersHaveEqualNumberOfOccurrences1941Test.java](../src/test/java/com/leetcode/easy/CheckIfAllCharactersHaveEqualNumberOfOccurrences1941Test.java) |
 | 2011 | [Final Value of Variable After Performing Operations](https://leetcode.com/problems/final-value-of-variable-after-performing-operations/) | [FinalValueOfVariableAfterPerformingOperations2011.java](../src/main/java/com/leetcode/easy/FinalValueOfVariableAfterPerformingOperations2011.java) | [FinalValueOfVariableAfterPerformingOperations2011Test.java](../src/test/java/com/leetcode/easy/FinalValueOfVariableAfterPerformingOperations2011Test.java) |
 | 2032 | [Two Out of Three](https://leetcode.com/problems/two-out-of-three/) | [TwoOutOfThree2032.java](../src/main/java/com/leetcode/easy/TwoOutOfThree2032.java) | [TwoOutOfThree2032Test.java](../src/test/java/com/leetcode/easy/TwoOutOfThree2032Test.java) |

src/main/java/com/leetcode/easy/ConcatenationOfArray1929.java

@@ -0,0 +1,27 @@
+// Tags: Array
+package com.leetcode.easy;
+
+/**
+ * <p><b>Time Complexity:</b> O(n)
+ * <ul>
+ *   <li>Single loop through 2n elements, where n = nums.length</li>
+ *   <li>Each iteration performs O(1) operations (modulo and array access)</li>
+ *   <li>Total: O(2n) = O(n)</li>
+ * </ul>
+ *
+ * <p><b>Space Complexity:</b> O(n)
+ * <ul>
+ *   <li>Result array of size 2n is allocated</li>
+ *   <li>No additional significant space used</li>
+ *   <li>Total: O(2n) = O(n)</li>
+ * </ul>
+ */
+public class ConcatenationOfArray1929 {
+    public int[] getConcatenation(int[] nums) {
+        int[] ans = new int[nums.length * 2];
+        for (int i = 0; i < nums.length * 2; i++) {
+            ans[i] = nums[i % nums.length];
+        }
+        return ans;
+    }
+}

src/test/java/com/leetcode/easy/ConcatenationOfArray1929Test.java

@@ -0,0 +1,25 @@
+package com.leetcode.easy;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+public class ConcatenationOfArray1929Test {
+
+    @Test
+    void testExample1() {
+        ConcatenationOfArray1929 solution = new ConcatenationOfArray1929();
+        int[] nums = {1, 2, 1};
+        int[] expected = {1, 2, 1, 1, 2, 1};
+        int[] result = solution.getConcatenation(nums);
+        assertArrayEquals(expected, result);
+    }
+
+    @Test
+    void testExample2() {
+        ConcatenationOfArray1929 solution = new ConcatenationOfArray1929();
+        int[] nums = {1, 3, 2, 1};
+        int[] expected = {1, 3, 2, 1, 1, 3, 2, 1};
+        int[] result = solution.getConcatenation(nums);
+        assertArrayEquals(expected, result);
+    }
+}