洛谷 P1865 A % B Problem

水题水题

#include<cstdio>
#include<vector>
#include<cstring>
#define _for(i, a, b) for(int i = (a); i <= (b); i++)
#define REP(i, a, b) for(int i = (a); i < (b); i++)
using namespace std;const int MAXN = 1123456;
bool is_prime[MAXN];
vector<int> prime;
int ans[MAXN];void get_prime()
{memset(is_prime, true, sizeof(is_prime));is_prime[0] = is_prime[1] = false;REP(i, 2, MAXN){if(is_prime[i]) prime.push_back(i);REP(j, 0, prime.size()){if(i * prime[j] >= MAXN) break;is_prime[i * prime[j]] = false;if(i % prime[j] == 0) break;}ans[i] = ans[i-1] + is_prime[i];}
}int main()
{get_prime();int n, m, l, r;scanf("%d%d", &n, &m);while(n--){scanf("%d%d", &l, &r);if(l < 1 || r > m) puts("Crossing the line");else printf("%d\n", ans[r] - ans[l-1]);}return 0;
}