add: 220208

2202/220208.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+
+/**
+ * 258. Add Digits
+ * Given an integer `num`, repeatedly add all its digits until the result has only one digit, and return it.
+ */
+
+class Solution {
+public:
+	static constexpr int addDigits(int num) {
+		int ret = 0;
+		for (; num; num /= 10)
+			ret += num % 10;
+		return ret < 10 ? ret : addDigits(ret);
+	}
+};
+
+int main() {
+	std::cout << Solution::addDigits(38);
+	return 0;
+}

2202/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2202)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2202 220207.cpp)
+ADD_EXECUTABLE(2202 220208.cpp)