总结:
题意:
将一个数(N>=2)最少分成多少个素数?
代码:
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
#include<string.h>
#include<map>
#include<queue>
#include<cmath>
#include<vector>
using namespace std;
typedef long long ll;
bool isprime(ll x){
ll mid=sqrt(x);
for(int i=2;i<=mid;i++){
if(x%i==0)return false;
}
return true;
}
int main(){
ll n;
while(~scanf("%lld",&n)){;
if(n&1){
if(isprime(n))cout<<1<<endl;
else if(isprime(n-2))cout<<2<<endl;
else cout<<3<<endl;
}else{
if(n==2)cout<<1<<endl;
else cout<<2<<endl;
}
}
return 0;
}