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Welcome to KismetOI Round 7「Spring Shadow Contest」!
I HEARD THAT IF YOU JUST PARTICIPATE, SOYO WILL SHOUT AT YOU, "WHY DO YOU HAVE TO PLAY 【 】?" I TRIED IT — IT'S FAKE NEWS. BECAUSE SOYO IS ALREADY MARRIED TO ANON, AND APPARENTLY NONE OF THE PROBLEMS IN THIS ROUND ARE THEMED AROUND MYGO!!!!! OR AVE MUJICA.
BUT THIS REALLY IS KISMETOI ROUND 7「SPRING SHADOW CONTEST」, AND EVERYONE IS WELCOME TO JOIN!
THE ROUND IS HOSTED BY HARMIS_YZ. THE PROBLEM DIFFICULTY RANGES ROUGHLY FROM POPULARIZATION LEVEL TO PROVINCIAL SELECTION LEVEL, WITH A TOTAL DURATION OF 4 HOURS, FOLLOWING THE IOI FORMAT. THE PROBLEMS ARE GENERALLY SORTED IN ASCENDING ORDER BASED ON THE SETTER'S SUBJECTIVE DIFFICULTY EVALUATION.
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START:
T1:
读题耗时 50min50 min50min，感觉没读懂，接着读。
60min60min60min终于理解了，开始敲。
尝试利用整个序列的峰值查询 + 二分AKAKAK此题，拿了10pts10pts10pts. 看来思路有误，接着改。
重新理解题意。
查询 ?k、i1、i2...ik?k、i_1、i_2 ... i_k?k、i1 、i2 ...ik ，返回 j1j2...jtj_1 j_2 ... j_tj1 j2 ...jt ，其中每个 jjj 满足：
Aij>max(Aij−1,Aij+1)A_{i_j}>max(A_{i_{j-1}}, A_{i_{j+1}})Aij >max(Aij−1 ,Aij+1 )
注意：返回的是 jjj（在查询序列中的下标位置），不是 iji_jij 的值。
再次敲。
继续尝试二分。
结果输出
看来还是不行，尝试暴力。
好像有点思路了，优化到了O(logn)O(logn)O(logn)，不知道能不能过。
写挂了，不打了。
70pts70pts70pts遗憾落幕
