add: 220213-CN

2202/220213.cpp

@@ -0,0 +1,35 @@
+#include <vector>
+#include <cstdio>
+
+/**
+ * 78. Subsets
+ * Given an integer array nums of unique elements, return all possible subsets (the power set).
+ * The solution set must not contain duplicate subsets. Return the solution in any order.
+ */
+
+class Solution {
+public:
+	static std::vector<std::vector<int>> subsets(const std::vector<int>& nums) {
+		int s = (1 << nums.size()), n = nums.size();
+		std::vector<std::vector<int>> ret(s);
+		for (int i = 0; i < s; ++i) {
+			std::vector<int>& t = ret[i];
+			t.reserve(n);
+			for (int j = 0; j < n; ++j)
+				if (i & (1 << j))
+					t.push_back(nums[j]);
+		}
+		return ret;
+	}
+};
+
+int main() {
+	const auto ret = Solution::subsets({1,2,3});
+	for (const auto& i : ret) {
+		for (const auto& j : i) {
+			std::printf("%d ", j);
+		}
+		std::printf("\n");
+	}
+	return 0;
+}

2202/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2202)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2202 220213-CN.cpp)
+ADD_EXECUTABLE(2202 220213.cpp)