???????????????д??Ч???????????????????????????????????????????Χ????????????????????????????????????????????????????????????μ?TopCoder????Challenge?????????????????????????????????????????????????????????ɡ?

????????????????????TopCoder????????????????????????????????????????????????????????????????????????????????????TopCoder???????SRM(Single Round Match)???????????????Σ????4??С?????????????????μ?????????????????????????????????20???????Room??????????75?????????3???????????????????????????C++??Java????????????????????????????з????????????????????????????????????????????????????????????????????????????????????÷???????????????????????????????У??????????????????÷?????0??SRM????????????75???????????????????????????????????15?????Challenge???????????λ?????????????Room????????????????????????????????????????????Challenge????????????????????????????????????Challenge?????Challenger??????????50???Defender????????????????????????????????????????????????Challenge????Challenger?????25???Defender????????Challenge???????????????????????TopCoder????θ????????У??λ???3?????????д????????????12?γ??Challenge??????????600????????????Room??????????????????????飡

?????????????Challenge??????????????????Ч???????????????bug???????????????е????????SRM??Challenge???????????????????????bug???????????

??????????????????????????originalWord??finalWord?????????'a'??'b'??????????originalWord?е?????????'a'????'b'??????'b'????'a'??????move????????????k?????????????k??move??originalWord???finalWord?????????????????????"POSSIBLE"????????"IMPOSSIBLE"??

??????????

????1?? originalWord="aababba"?? finalWord="bbbbbbb"??k=2??????originalWord????4???????finalWord????????2??move???????originalWord???finalWord???????"IMPOSSIBLE"??

????2?? originalWord="aabb"?? finalWord="aabb"??k=1??????originalWord??finalWord???????????1??move???????originalWord??finalWord??????????"IMPOSSIBLE"??

????3?? originalWord="aaa"?? finalWord="bab"??k=4???????"POSSIBLE"??move???????????aaa -> baa -> bab -> aab -> bab??

?????????????????????????????????originalWord??finalWord?в??????????diff?????diff??k???????ɡ????diff????k????????????"IMPOSSIBLE"????????move??????????????diff????k??????????"POSSIBLE"?????diffС??k??????????(k-diff)???????????(k-diff)????????÷???"POSSIBLE"?????????????move???????????????????move??????'a'????'b'??????'b'???'a'??????????????(k-diff)??????????????"IMPOSSIBLE"?????????????move???????????????

??????????????????????????????????ж???????????????????д???????

?????????????д??????????￡??????????????????????￡????濴???????Challenge?????

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