add: 220504-CN [cpp]

cpp/2205/220504-CN.cpp

@@ -0,0 +1,35 @@
+#include <cstdio>
+
+/**
+ * 1823. Find the Winner of the Circular Game
+ * There are n friends that are playing a game. The friends are sitting in a circle and are numbered from 1 to n in clockwise order. More formally, moving clockwise from the ith friend brings you to the (i+1)th friend for 1 <= i < n, and moving clockwise from the nth friend brings you to the 1st friend.
+ *
+ * The rules of the game are as follows:
+ *
+ * Start at the 1st friend.
+ * Count the next k friends in the clockwise direction including the friend you started at. The counting wraps around the circle and may count some friends more than once.
+ * The last friend you counted leaves the circle and loses the game.
+ * If there is still more than one friend in the circle, go back to step 2 starting from the friend immediately clockwise of the friend who just lost and repeat.
+ * Else, the last friend in the circle wins the game.
+ * Given the number of friends, n, and an integer k, return the winner of the game.
+ */
+
+class Solution {
+private:
+	static int helper(int n, int k) {
+		if (n <= 1)
+			return 0;
+		return (helper(n - 1, k) + k) % n;
+	}
+public:
+	static int findTheWinner(int n, int k) {
+		if (k <= 1)
+			return n;
+		auto ans = (helper(n, k) + 1) % n;
+		return ans ? ans : n;
+	}
+};
+
+int main() {
+	std::printf("%d\n", Solution::findTheWinner(5, 2));
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220503.cpp)
+ADD_EXECUTABLE(2204 220504-CN.cpp)