feat(cpp): add josephus.cpp

Author: ongshunping

cpp/Math and Geometry/josephus.cpp

@@ -0,0 +1,10 @@
+int josephus(int n, int k) {
+    // Base case: If there's only one person, the last person is person 0.
+    if (n == 1) {
+        return 0;
+    }
+    // Calculate the position of the last person remaining in the reduced problem 
+    // with 'n - 1' people. We use modulo 'n' to ensure the answer doesn't exceed
+    // 'n - 1'.
+    return (josephus(n - 1, k) + k) % n;
+}