luogu P2064 奇妙的汽车 爆搜

#include<map>
#include<queue>
#include<time.h>
#include<limits.h>
#include<cmath>
#include<ostream>
#include<iterator>
#include<set>
#include<stack>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define rep_1(i,m,n) for(int i=m;i<=n;i++)
#define mem(st) memset(st,0,sizeof st)
inline int read()
{
    int num=0, w=0;
    char ch=0;
    while (!isdigit(ch))
    {
        w|=ch=='-';
        ch = getchar();
    }
    while (isdigit(ch))
    {
        num = (num<<3) + (num<<1) + (ch^48);
        ch = getchar();
    }
    return w? -num: num;
}
typedef long long ll;
typedef pair<int,int> pii;
typedef unsigned long long ull;
typedef pair<double,double> pdd;
const int inf = 0x3f3f3f3f;
int n,ans=inf;
void dfs(int dep,int num)
{
    if(!num)
    {
        ans=min(ans,dep);//边界条件
        return ;
    }
    num--;//把式子里面的1减掉
    for(int i=2; i<=9; i++) //枚举k
        if(!(num%i)) //判断整除
            dfs(dep+1,num/i);
}
void solve()
{
    cin>>n;
    for(int i=1; i<=sqrt(n); i++)
        if(!(n%i))
        {
            if(n/i!=n)
                dfs(0,i);//n/(n/i)=i
            if(i!=n)
                dfs(0,n/i);//n/i
        }
    if(ans!=inf)
        cout<<ans<<endl;//判断能否到达
    else
        cout<<-1<<endl;
}
int main()
{
    int t=1;
    while(t--)
        solve();
    return 0;
}