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[CC XXOR]Chef and Easy Problem 题目大意: 给你一个长度为$n(n\le10^5)$的序列$A(A_i include inline int getint() { register char ch; while(!isdigit(ch=getchar())); regi 阅读全文
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[BZOJ2124]等差子序列/[CF452F]Permutation 题目大意: 一个$1\sim n$的排列$A_{1\sim n}$,询问是否存在$i,j(i include include inline int getint() { register char ch; while(!isdi 阅读全文