在本题题解中

for (int l1 = 0; l1 < s.size(); ++l1) if (s.substr(l1, 7) == "Genshin") {
  for (int l2 = l1; l1 < s.length(); ++l2) if (s.substr(l2, 6) == "player") {
    ++ans;
  }
}

第二行应当是

for (int l2 = l1; l2 < s.length(); ++l2)

正如zhaojiadong2022在另一篇帖子中所述，参照原题解会发生如下错误：
terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::substr: __pos (which is 20) > this->size() (which is 19)

特此补充说明，蒟蒻知之甚少，有错误之处请神犇帮忙改正。