diff --git a/2201/220126-CN.cpp b/2201/220126-CN.cpp
new file mode 100644
index 0000000..593f269
--- /dev/null
+++ b/2201/220126-CN.cpp
@@ -0,0 +1,104 @@
+#include <unordered_set>
+#include <unordered_map>
+#include <vector>
+#include <iostream>
+
+namespace std {
+	template<>
+	struct hash<std::pair<int, int>> {
+		inline std::size_t operator()(const std::pair<int, int>& v) const {
+			return std::hash<int>()(v.first) ^ std::hash<int>()(v.second);
+		}
+	};
+}
+
+class DetectSquaresOld {
+private:
+	std::unordered_multiset<std::pair<int, int>> s;
+public:
+	DetectSquaresOld() = default;
+
+	void add(const std::vector<int>& point) {
+		s.insert(std::make_pair(point[0], point[1]));
+	}
+
+	int count(const std::vector<int>& point) const {
+		int ret = 0;
+		// Point 1
+		auto p1 = std::make_pair(point[0], point[1]);
+		// Point 2's have same X index as Point 1.
+		std::vector<std::pair<int, int>> p2s;
+		std::copy_if(s.begin(), s.end(), std::back_inserter(p2s), [&](const std::pair<int, int>& v) { return v.first == p1.first && v.second != p1.second; } );
+		for (const auto& p2 : p2s) {
+			// Now, we know what Point 3 and Point 4 looks like.
+			// Point 1 is (x, y)
+			// Point 2 is (x, y + dist)
+			// Point 3 is (x +/- dist, y + dist)
+			// Point 4 is (x +/- dist, y)
+			ret += s.count(std::make_pair(p1.first + (p2.second - p1.second), p2.second)) * s.count(std::make_pair(p1.first + (p2.second - p1.second), p1.second));
+			ret += s.count(std::make_pair(p1.first - (p2.second - p1.second), p2.second)) * s.count(std::make_pair(p1.first - (p2.second - p1.second), p1.second));
+			/*
+			ret += std::count_if(s.begin(), s.end(), [&](const std::pair<int, int>& v) {
+				// Point 3, +
+				return (v.second == p2.second) && (v.first == p1.first + (p2.second - p1.second));
+			}) * std::count_if(s.begin(), s.end(), [&](const std::pair<int, int>& v) {
+				// Point 4, +
+				return (v.second == p1.second) && (v.first == p1.first + (p2.second - p1.second));
+			}) + std::count_if(s.begin(), s.end(), [&](const std::pair<int, int>& v) {
+				// Point 3, -
+				return (v.second == p2.second) && (v.first == p1.first - (p2.second - p1.second));
+			}) * std::count_if(s.begin(), s.end(), [&](const std::pair<int, int>& v) {
+				// Point 4, -
+				return (v.second == p1.second) && (v.first == p1.first - (p2.second - p1.second));
+			});
+			 */
+		}
+		return ret;
+	}
+};
+
+class DetectSquares {
+private:
+	std::unordered_multiset<int> indexX[1002], indexY[1002];
+public:
+	DetectSquares() = default;
+
+	void add(const std::vector<int>& point) {
+		indexX[point[0]].insert(point[1]);
+		indexY[point[1]].insert(point[0]);
+	}
+
+	int count(const std::vector<int>& point) const {
+		int ret = 0;
+		// Point 2's have same X index as Point 1.
+		std::unordered_map<int, int> p2s;
+		for (const int p2Y : indexX[point[0]]) {
+			if (p2Y != point[1]) {
+				++p2s[p2Y];
+			}
+		}
+		for (const auto& p2C : p2s) {
+			// Now, we know what Point 3 and Point 4 looks like.
+			// Point 1 is (x, y)
+			// Point 2 is (x, y + dist)
+			// Point 3 is (x +/- dist, y + dist)
+			// Point 4 is (x +/- dist, y)
+			int dist = p2C.first - point[1];
+			ret += indexY[p2C.first].count(point[0] + dist) * indexY[point[1]].count(point[0] + dist) * p2C.second;
+			ret += indexY[p2C.first].count(point[0] - dist) * indexY[point[1]].count(point[0] - dist) * p2C.second;
+		}
+		return ret;
+	}
+};
+
+int main() {
+	DetectSquares detectSquares;
+	detectSquares.add({3, 10});
+	detectSquares.add({11, 2});
+	detectSquares.add({3, 2});
+	std::cout << std::endl << detectSquares.count({11, 10});
+	std::cout << std::endl << detectSquares.count({14, 8});
+	detectSquares.add({11, 2});
+	std::cout << std::endl << detectSquares.count({11, 10});
+	return 0;
+}
\ No newline at end of file
diff --git a/2201/CMakeLists.txt b/2201/CMakeLists.txt
index 54f87c2..e96eb06 100644
--- a/2201/CMakeLists.txt
+++ b/2201/CMakeLists.txt
@@ -3,4 +3,4 @@ PROJECT(2201)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2201 220125.cpp)
+ADD_EXECUTABLE(2201 220126-CN.cpp)