7問目。
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10001st prime number?
#include <iostream> using namespace std; long long int primeCall(unsigned int NM){ long long int prime[50000]; long long int *box=new long long int[1000000]; long long int p=0; for(p=0;p<NM;p++)prime[p]=0; prime[0]=2; box[0]=0; for(p=1;p<=NM;p++) { for(long long int i=prime[p-1];i<1000000;i++) { if((i%prime[p-1])==0)box[i]=0; else if (box[i]!=0)box[i]=i; } for(long long int i=2;i<1000000;i++) { if(box[i]!=0) { prime[p]=i; break; } } } delete [] box; return prime[NM-1]; } int main() { cout<<primeCall(10001)<<endl; }