1007. 素数对猜想 (20)

#include<stdio.h>   #include<math.h> //sqrtbool sushu(int x){for(int i=2;i<=sqrt(x);i++){if(x%i==0) return false;}return true;}int main(){// 2,3,5,7,11,13,17,19,23,29,,,,,int N;scanf("%d",&N);int prePn=2,Pn=3,count=0;for(int j=4;j<=N;j++){if(sushu(j)){prePn=Pn;Pn=j;if(Pn-prePn==2) count++;}}printf("%d\n",count);return 0;}