For the following problem 543A - Writing Code, the jury's solution 11035704 optimize the DP solution explained in the contest's editorial http://codeforces.net/blog/entry/17773.
I understood the approach explained in the editorial, but what's the intuition behind the optimization and how it works? Specially the lines with bitwise operations:
int i = it & 1;
...
z[i][j][k] = z[i ^ 1][j][k];
...
ans += z[n & 1][bl][i];
...
Thanks.