Merge pull request #13 from tannuchoudhary/patch-5

Create SamAndSubstring.cpp

Author: Mehulcoder

DP1(Very important)/SamAndSubstring.cpp

@@ -0,0 +1,15 @@
+/*Hackerrank problem "sam and substring"*/
+
+int substrings(string n) {
+
+long long total_sum = n[0]-'0';
+long long last_value = n[0] - '0';
+
+for(int i=1; i<n.length(); i++){
+    last_value = ((last_value*10)+((n[i]-'0')*(i+1)))%1000000007;
+    total_sum = (total_sum + last_value)%1000000007;
+}
+return total_sum;
+}
+
+