Concatenation of Array

CMakeLists.txt

@@ -94,6 +94,7 @@ add_task(combination-sum-ii)
 add_task(combination-sum-iii)
 add_task(combination-sum-iv)
 add_task(combinations)
+add_task(concatenation-of-array)
 add_task(construct-binary-tree-from-inorder-and-postorder-traversal)
 add_task(construct-binary-tree-from-preorder-and-inorder-traversal)
 add_task(construct-quad-tree)
@@ -435,9 +436,9 @@ add_task(plus-one)
 add_task(populating-next-right-pointers-in-each-node)
 add_task(populating-next-right-pointers-in-each-node-ii)
 add_task(possible-bipartition)
-add_task(powx-n)
 add_task(power-of-three)
 add_task(power-of-two)
+add_task(powx-n)
 add_task(predict-the-winner)
 add_task(product-of-array-except-self)
 add_task(product-of-the-last-k-numbers)

solutions/concatenation-of-array/CMakeLists.txt

@@ -0,0 +1 @@
+add_catch(test_concatenation_of_array test.cpp)

solutions/concatenation-of-array/solution.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <algorithm>
+#include <vector>
+
+class Solution {
+public:
+  static std::vector<int> getConcatenation(const std::vector<int> &nums) {
+    const auto n = nums.size();
+
+    std::vector<int> res(2 * n);
+    for (size_t i = 0; i < n; ++i) {
+      res[i] = res[i + n] = nums[i];
+    }
+
+    return res;
+  }
+};

solutions/concatenation-of-array/test.cpp

@@ -0,0 +1,16 @@
+#include <catch.hpp>
+
+#include <solution.hpp>
+
+TEST_CASE("Simple") {
+  {
+    std::vector<int> nums{1, 2, 1};
+    std::vector<int> expected{1, 2, 1, 1, 2, 1};
+    REQUIRE(expected == Solution::getConcatenation(nums));
+  }
+  {
+    std::vector<int> nums{1, 3, 2, 1};
+    std::vector<int> expected{1, 3, 2, 1, 1, 3, 2, 1};
+    REQUIRE(expected == Solution::getConcatenation(nums));
+  }
+}