hdu 4715 Difference Between Primes （二分查找）

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 using namespace std;
 6 int zj[5000000];
 7 int ssb[5000000],pn;
 8 void f()
 9 {
10     int i,j;
11     memset(zj,0,sizeof(zj));
12     zj[0]=zj[1]=1;
13     pn=0;
14     for (i=2;i<=5000000;i++)
15     {
16         if (!zj[i]) {ssb[pn]=i;pn++;}
17         for (j=0;j<pn;j++)
18         {
19             if (i*ssb[j]>5000000) break;
20             zj[i*ssb[j]]=1;
21             if (i%ssb[j]==0) break;
22         }
23     }
24 }
25 int main()
26 {
27     int t,n,i,c;
28     f();
29     scanf("%d",&t);
30     while (t--)
31     {
32         scanf("%d",&n);
33         for (i=0;i<pn;i++)
34         {
35            c=lower_bound(ssb,ssb+pn,ssb[i]+n)-ssb;
36            if (ssb[c]==ssb[i]+n)
37            {
38                printf("%d %d\n",ssb[c],ssb[i]);
39                break;
40            }
41         }
42     }
43 }