hdu 4715 Difference Between Primes （打表 枚举）

Difference Between PrimesTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 528 Accepted Submission(s): 150

Problem DescriptionInputOutputSample InputSample OutputSource#include <iostream>#include <cstdio>#include <cstring>#include <cmath>#define maxn 10000005using namespace std;int n,m,cxx,ans;bool vis[maxn];int prime[664580];void sieve(int nn){ int i,j,mm; mm=int(sqrt(nn+0.5)); memset(vis,0,sizeof(vis)); for(i=2;i<=mm;i++) { if(!vis[i]) { for(j=i*i;j<=nn;j+=i) { vis[j]=1; } } }}int get_prime(int nn){ int i,c=0; sieve(nn); for(i=2;i<=nn;i++) { if(!vis[i]) prime[c++]=i; } return c;}bool isprime(int x){ int i,j,t; t=sqrt(x+0.5); for(i=2;i<=t;i++) { if(x%i==0) return false ; } return true ;}int main(){ int i,j,t,a,b,flag,sgn; cxx=get_prime(10000000); // 664579 scanf("%d",&t); while(t--) { scanf("%d",&n); flag=0; if(n>=0) sgn=1; else sgn=0,n=-n; for(i=0;i<cxx;i++) { b=prime[i]; a=b+n; if(isprime(a)) { flag=1; if(sgn) printf("%d %d\n",a,b); else printf("%d %d\n",b,a); break ; } } if(!flag) printf("FAIL\n"); } return 0;}

1楼u011032846昨天 20:42

For each number xtested, outputstwo primes aand bat one line separatedwith one space where a-b=x. nn就是说不用处理x是负数的情况啊。。

Re: u010228612昨天 22:56

回复u011032846n不是吧 好歹你英语那么好！