【题解】洛谷T48566[提高测试TG4]A.yyy送礼物 数学知识

题目链接 简单的数论题，手推一下答案为 2 n − 1 ∗ ∑ i = 1 n a i 2^{n-1}*\sum_{i=1}^na_i 2n−1∗∑i=1n​ai​ #include<cstdio> typedef long long ll; const ll mod=998244353; ll sum=0; int n,a; inline int read() { int s=0,t=1;ch

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