From e2dede4afaed810fe4d7becdd4acd001f55b8562 Mon Sep 17 00:00:00 2001
From: Arnab Bir <arnabbir@gmail.com>
Date: Tue, 23 Jan 2018 22:38:00 +0530
Subject: [PATCH] Create RecursiveDigitSum.cpp

---
 RecursiveDigitSum.cpp | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 RecursiveDigitSum.cpp

diff --git a/RecursiveDigitSum.cpp b/RecursiveDigitSum.cpp
new file mode 100644
index 0000000..429cca3
--- /dev/null
+++ b/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;
+}