I received the following message. Your solution 151524331 for the problem 1660C significantly coincides with solutions ttttan/151524331, mayocorn/151541772.

The reason for coinciding is the use of AtCoder Library (ACL blog link). ACL is the official source code. I always use much of the ACL source code, and mayocorn also do the same thing. Please look at these codes(151524331,151541772). I used dynamic programming (dp) for the problem, but mayocorn solved differently. The main logic of these solutions are different.