hdu 5104 素數打表水題

http://acm.hdu.edu.cn/showproblem.php?pid=5104

找元組數量，滿足p1<=p2<=p3且p1+p2+p3=n且都是素數

不用素數打表都能過，數據弱的一比

#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <queue>
#include <map>
#include <iostream>
#include <sstream>
#include <algorithm>
using namespace std;
#define RD(x) scanf("%d",&x)
#define RD2(x,y) scanf("%d%d",&x,&y)
#define RD3(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define clr0(x) memset(x,0,sizeof(x))
#define clr1(x) memset(x,-1,sizeof(x))
#define eps 1e-9
const double pi = acos(-1.0);
typedef long long LL;
const int inf = 0x7fffffff;
const int maxn = 1e5+5;
int p[maxn],pr[maxn],cnt = 0;
int n;
void init()
{
    clr0(p);
    for(int i = 2;i < maxn;++i){
        if(!p[i]){
            for(int j = i + i;j < maxn;j+=i)
                p[j] = 1;
        }
    }
    p[0] = 1;
    for(int i = 2;i < maxn;++i)
        if(!p[i])
            pr[cnt++] = i;
}
int main()
{
    init();//cout<<cnt;
    while(~RD(n)){
        LL ans = 0;
        for(int i = 0;i < cnt;++i){
            if(n < pr[i]*3)
                break;
            for(int j = i;j < cnt;++j){
                int k = n - pr[i] - pr[j];
                if(pr[j] > k)
                    break;
                //printf("%d %d %d \n",pr[i],pr[j],k);
                if(!p[k])
                    ans++;
            }
        }
        printf("%I64d\n",ans);
    }
    return 0;
}