Create RecursiveDigitSum.cpp

RecursiveDigitSum.cpp

@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int digitSum(string n, int k) {
+
+    if(n.length() == 1 && k == 1){
+        return (int) (n[0]-'0');
+    }
+    long sum = 0;
+    if( k == 1){
+        for(int i = 0; i < n.length(); ++i){
+            sum += (int) (n[i] - '0');
+        }
+        return digitSum(to_string(sum), 1);
+    }
+    else{
+        return digitSum(to_string(k * (int)digitSum(n , 1)),1);
+    }
+
+}
+
+int main() {
+    string n;
+    int k;
+    cin >> n >> k;
+    int result = digitSum(n, k);
+    cout << result << endl;
+    return 0;
+}