hdu 1319

水题，打素数表即可，都用不着筛法。

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <cmath>
using namespace std;

const int MAXI = 200;
const int MAXV = 1100;
int prime[MAXI], I;
int facnum[MAXV];

void init() {
    I = 0;
    memset(prime, 0, sizeof(prime));
    prime[I++] = 1;
    prime[I++] = 2;
    int sqr, j;
    for (int i = 3; i < MAXV; i++) {
        sqr = (int) sqrt(i);
        for (j = 2; j <= sqr; j++) {
            if (i % j == 0) {
                break;
            }
        }
        if (j > sqr) {
            prime[I++] = i;
        }
    }
    memset(facnum, 0, sizeof(facnum));
    j = 0;
    for (int i = 1; i < MAXV; i++) {
        if (i == prime[j]) {
            j++;
        }
        facnum[i] = j;
    }
}

void myprint(int i, int j) {
    for (; i < j; i++) {
        printf(" %d", prime[i]);
    }
    putchar('\n');
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    init();
    int N, C, num, s, e;
    while (scanf("%d%d", &N, &C) == 2) {
        printf("%d %d:", N, C);
        num = 2 * C;
        if (facnum[N] % 2 == 1) {
            num--;
        }
        s = 0;
        e = facnum[N];
        if (num < facnum[N]) {
            s = (facnum[N] - num) / 2;
            e = facnum[N] - s;
        }
        myprint(s, e);
        putchar('\n');
    }
    return 0;
}