Hi all,
I have difficulty on a problem on codeforces http://codeforces.net/problemset/problem/691/D
my submission is : http://codeforces.net/contest/691/submission/19308291
I think my idea is right, I used dsu to group several numbers and downsort numbers inside the groups. But I don't know why I am still wrong answer at test21. The idea is simple, but I can't find what's wrong. Anyone please help me, thanks:D
How to find bugs when you think your algorithms and implementation is correct,BTW?
Edit: Bug found:)))
I should calculate p[i]=parent(i) before I use p[i] . I thought it was automatically done by merging, however it is not :DDDD
Here is AC version of your submission. You should re-check the parent of every node.