message: Update shifting-letters.cpp
diff: @@ -8,10 +8,7 @@ public:
  auto times = accumulate(shifts.cbegin(), shifts.cend(), 0L) % 26;
  for (int i = 0; i < S.length(); ++i) {
  result.push_back('a' + (S[i] - 'a' + times) % 26);
  - times = (times - shifts[i]) % 26;
  - if (times < 0) {
  - times += 26;
  - }
  + times = ((times - shifts[i]) % 26 + 26) % 26;
  }
  return result;
  }
  