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素数筛法+二分可以过#include <iostream> #include <cstdio> #include <algorithm> using namespace std; #define MAXN 1000010 #define ll long long int n; int Prime[MAXN]; bool NotPrime[MAXN]; int pcnt; void InitPrime(int n) { for(ll i=2;i<=n;i++) { if(!NotPrime[i]) { Prime[pcnt++]=i; for(ll j=i*i;j<=n;j+=i) NotPrime[j]=true; } } } int main() { InitPrime(999999); while(scanf("%d",&n),n) { for(int i=0;i<pcnt;i++) { int a=Prime[i]; int b=*lower_bound(Prime,Prime+pcnt,n-a); if(a+b==n) { printf("%d = %d + %d\n",n,a,b); break; } } } return 0; } Followed by: Post your reply here: |
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