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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | #include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<stack>using namespace std;void isPrime(int a[]){ for(int i=0;i<10007;i++) { a[i] = 1; } a[0] = a[1] = 0; for(int i=2;i<((10007+1)>>1);i++) { if(a[i]) { for(int j=(i<<1);j<10007;j+=i) a[j] = 0; } }}int main(){ int prime[10007]; isPrime(prime); int a; while(scanf("%d",&a)!=EOF) { a = (a>>1); int ans1 = a,ans2 = a; while(1) { if(prime[ans1] && prime[ans2]) break; ans1--; ans2++; } printf("%d %d\n",ans1,ans2); } return 0;} |
原文：http://www.cnblogs.com/liwenchi/p/7259372.html