PE 118-119 (dfs+暴力)-蒲公英云

PE 118-119 (dfs+暴力)

PE 118

题解：next_permutation()+dfs就可以了

代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int ans=0;
vector<int>v;
int isprime(ll n)
{
    if(n==1)return 0;
    for(ll i=2;i*i<=n;i++){
        if(n%i==0)return 0;
    }
    return 1;
}
void dfs(int pos,ll now){
    if(pos>=9){
        if(ans<=10){
            //for(int i=0;i<9;i++)
            //cout<<v[i]<<" ";
            //cout<<endl;
        }
        ans++;return; 
    }
    ll n = 0;
    while(pos < 9){
        n *= 10;
        n += v[pos];
        if(isprime(n) && n >= now){
            dfs(pos+1,n);
        }
        pos++;
    }
}
int main()
{
    for(int i=1;i<=9;i++){v.push_back(i);}
    do{
        dfs(0,0);
    }while(next_permutation(v.begin(),v.end()));
    cout<<"ans="<<ans<<endl;
    return 0;
}

PE 119

题解：暴力….

代码：

#include<bits/stdc++.h>
using namespace std;
long long gao(int m,int n)
{
    long long  res=(long long)pow(m,n);
    long long ans=0;
    while(res)
    {
        ans+=res%10;
        res/=10;
    }
    return ans;
}
set<long long>s;
int main()
{
    for(int i=1;i<=100;i++)
    {
        for(int j=1;j<=100;j++)
        {
            if((long long)gao(j,i)==(long long)j)
            {
                s.insert(pow(j,i));
            }
        }
    }
    int num=1;
    for(set<long long>::iterator it = s.begin();it !=s.end();it++)
    {
        if(*it>=10)
        cout<<num++<<":"<<*it<<endl;
    }
    return 0;
}