1007. 素数对猜想 (20)

#include<stdio.h>//有待改进
	int main(){
		int n;
		scanf("%d",&n); 
		int kirby[n];
		for (int i = 0;i < n;i++){
			kirby[i] = 0;
		}
		kirby[0] = 3;
		int cnt = 1;
		int isprime = 1;
		int i = 3;
		while (i <= n){
			isprime = 1;
			for (int j = 1;j < cnt / 2;j++){//这里不太清楚到底是根号快还是这样快，，，，，//for (int j = 0;kirby[j] < sqrt(i) + 1&&j < cnt;j++){
				if (i % kirby[j] == 0){
					isprime = 0;
					break;
				}
			}
			if (isprime){
				kirby[cnt] = i;
				cnt++;
			}
			i += 2;
		}
		int cnt1 = 0; 
		for (int i = 0;i < n - 1;i++){
			if (kirby[i + 1] - kirby[i] == 2){
				cnt1++;
			}
		}
		printf("%d",cnt1);
		return 0;
}