Sam and substrings Discussions | Algorithms | HackerRank
  • + 0 comments

    I am not sure if others used the same logic, but the idea is that for the current sum, we multiply the previous sum by 10 and then add "extra". This "extra" grows each iteration, specially by the 1-based index of the current digit times the current digit value. For example, if the current digit is 3 and the 1-based index of this digit is 4, then the "extra" would increase by 12. So at any given digit, the sum is: currentSum = previousSum*10 + (previousExtra + (index * currentDigit)).