题目链接 LOJ6165
题目意思其实就是求LCM(1, 2, 3, ..., n)
直接用线性筛求出1到1e8之间的所有质数
然后对于每个质数p,他对答案的贡献为$p^{i}$ 其中$p^{i}$小于等于n且要最大。
c数组可能很大,所以我开了bitset...
#include <bits/stdc++.h> using namespace std; #define rep(i, a, b) for (int i(a); i <= (b); ++i) #define dec(i, a, b) for (int i(a); i >= (b); --i) typedef long long LL; const int N = 6170736; const int M = 100000002; const LL mod = 100000007; int n, pn; int p[N]; bitset <M> c; LL ans = 1LL; int v; int main(){ scanf("%d", &n); pn = 0; rep(i, 2, n){ if (!c[i]){ p[++pn] = i; for (LL s = i; s <= n; s *= i) ans = ans * i % mod; } rep(j, 1, pn){ v = i * p[j]; if (v > n) break; c[v] = 1; if (i % p[j] == 0) break; } } printf("%lld ", ans); return 0; }