算法笔记5.4

前n个素数的求法:埃氏筛

leetcode204:https://leetcode-cn.com/problems/count-primes/

算法笔记5.4

素数也叫做质数

#include <iostream>
#include<map>
#include<string>
#include<cstdio>
using namespace std;
int arr[10000]={0};
int numberofprime(int num){

    int cnt=0;
    if(num<2)return 0;
    for(int i=2;i<=num;i++){
        if(arr[i]==0){
            cnt++;
            printf("%d ",i);
            for(int j=i+i;j<=num;j+=i){
                arr[j]=1;
            }
        }
    }
    return cnt;
}
int main()
{
    int n=100;
    scanf("%d",&n);
    n=numberofprime(n);
    printf("The Number of the Prime are:%d",n);
    return 0;
}