This is a teaser! Every time solution is just so, so close!
In the meantime the white beads are cause of black despair.
Here is the algorithm (I passed Usaco grader)
1) find first colored bead. say it is at position k in the n bead necklace
2) rearrange necklace: move the section 0-k to the end ,so it starts with true color.
e.g {wwbrwbrb{ becomes {brwbrbww}
3) cut up the necklace into sub-sections (array of strings), so that each section starts with a color e.g. {b rw b r bww}
4) if first and last segment are the same color, join them
e.g. {b rw bw rw bww} becomes {bwwb rw bw rw} (sequence is preserved)
5) Notice!!!! the second last element (bw) ends with white. So white can be joined to rw that follows.
Also notice that following sequence will never starts with white.
6) for each entry in the array of sub sequences add lengths of entry k and k+1.
Then skim the white spaces (if any) from the entry k-1 and add to the above (since this is a circle then k-1 entry may be the last in the array).
if bigger than max then change max.
There is some tricky accounting for less than three sub sequences in the necklace but it is just tedious, no trick to it.
