UVA-10200(素数)

    xiaoxiao2025-02-05  7

    Time Limit:3000MS     Memory Limit:0KB     64bit IO Format:%lld & %llu

    又是素数:

    #include<cstdio> #include<algorithm> #include<cmath> #define M(x) (x*x+x+41) int dp[10100]; bool judge(int x) { if(x<=1) return 0; for(int i=2;i*i<x+1;i++) { if(x%i==0) return 0; } return 1; } int main() { int a,b; for(int i=0;i<=10010;i++) dp[i]=judge(M(i)); while(~scanf("%d %d",&a,&b)) { int cnt=0; for(int i=a;i<=b;i++) cnt+=dp[i]; double ans=cnt*1.0/(b-a+1)*100+1e-8; //记着后面要加精度,不然就 WA 了 printf("%.2lf\n",ans); } return 0; }

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