摘要：题面:https://www.luogu.org/problemnew/show/P3901 cpp Code: include include include include include include include using namespace std; const int N=1000 阅读全文

摘要：题面:https://www.luogu.org/problemnew/show/P2709 cpp 本题的关键在于sum(n)² sum(n 1)²=sum(n)² sum(n)²+2 sum(n) 1=2 sum(n) 1 Code: include include include includ 阅读全文