contest 1.17

Posted 2021-02-03 lllxq

C.最大公约数II

分解因子+欧拉函数

#include <iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
typedef long long ll;
using namespace std;
 
ll ans1,asn2;
 
ll get_phi(ll x){
    ll ret=x;
    for(ll i=2;i*i<=x;i++)
      if(x%i==0){
        ret/=i,ret*=(i-1);
        while(x%i==0)x/=i;
      }
    if(x>1)ret/=x,ret*=x-1;
    return ret;
}
 
 
int main()
{
    ll n;scanf("%lld",&n);
    ll i;
    ll ans1,ans2;
    for(i=1;i*i<=n;i++){
        if(n%i==0){
            ans1=i;
            ans2=get_phi(n/i);
            printf("%lld %lld
",ans1,ans2);
        }
 
    }
    if(sqrt(n)*sqrt(n)==n) i-=2;
    else i-=1;
    for(i;i>=1;i--){
        if(n%i==0){
            ans1=n/i;
            ans2=get_phi(i);
            printf("%lld %lld
",ans1,ans2);
        }
    }
    return 0;
}

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A.花

dp