摘要： 题意:求有几组满足 a+b^2-c^3=0(mod k) 1<=a<=b<=c<=n (a,b,c)。思路：树状数组注意到 当b固定时 考虑a 1~b%k有b/k+1 b%k+1~k 有b/k个从大至小枚举b，每次tree[b^3%k]++ 查询 (1+b*b)%k~(b%k+b*b)%k 总和sum*(b/k+1)+(sum总-sum)*b/k 1 #include<iostream> 2 #include<cstdio> 3 #include<cmath> 4 #include<cstring> 5 using nam 阅读全文