diff --git a/cpp/more/0001.cpp b/cpp/more/0001.cpp
new file mode 100644
index 0000000..bc3b79e
--- /dev/null
+++ b/cpp/more/0001.cpp
@@ -0,0 +1,27 @@
+#include <vector>
+#include <unordered_set>
+
+/**
+ * 1. Two Sum
+ * Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
+ * You may assume that each input would have exactly one solution, and you may not use the same element twice.
+ * You can return the answer in any order.
+ */
+
+class Solution {
+public:
+	static std::vector<int> twoSum(const std::vector<int>& nums, int target) {
+		std::unordered_multiset<int> s(nums.begin(), nums.end());
+		for (int i : s) {
+			if (s.count(target - i) > (i == target - i ? 1 : 0)) {
+				int x = 0, y = nums.size() - 1;
+				while (nums[x] != i)
+					++x;
+				while (nums[y] != target - i)
+					--y;
+				return {x, y};
+			}
+		}
+		return {};
+	}
+};
diff --git a/cpp/more/CMakeLists.txt b/cpp/more/CMakeLists.txt
index 3dd6e05..7b4aa9b 100644
--- a/cpp/more/CMakeLists.txt
+++ b/cpp/more/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(more)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(more 0021.cpp)
+ADD_EXECUTABLE(more 0001.cpp)