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摘要：题目描述 题目分析 设$W=\sum\limits_{i=1}^nw_i$，$A=\sum\limits_{i=1}^nw_i[i\ is\ alive]$，$P_i$为下一个打中$i$的概率。 如果开枪打中了已经死亡的猎人，我们可以视作再开一枪，这样就不会产生影响，因此有 $$ \begin{sp 阅读全文

摘要：题面 Description 很久很久以前，有一只神犇叫yzy; 很久很久之后，有一只蒟蒻叫lty; Input 请你读入一个整数N;$1 include include include include include include include define MAXN 0x7fffffff t 阅读全文

摘要：题面 Description Input 一共T+1行 第1行为数据组数T(T include include include include include include include define MAXN 0x7fffffff typedef long long LL; const int 阅读全文

摘要：题面 Description 给出一个数字N，求$\sum\limits_{i=1}^n\varphi(i)$i,1 include include include include include include include define MAXN 0x7fffffff typedef long 阅读全文