Not solvable input

[bncunha]

Hello!

Your algorithm is awesome, but there are some inputs that is impossible to solve, like "812043765". You could check if is possible to solve before run the algorithm.

[dgurkaynak]

Hey @bncunha, thank you for reaching out, but this was my school assignment. Maybe one day if I got bored too much, I can fix that 😁Or, as always any PRs are welcome.

[HCsuperc]

这个只需要加一个判断即可：在初始化生成序列后，判断一下去掉0后的序列的逆序数是奇数还是偶数。奇数情况是无解的，这个条件下就重新生成。
如：812043765对应序列是 81243765的逆序数和是11，无解。12345687逆序数是1，无解。