长脖子鹿省选模拟赛 [LnOI2019SP]快速多项式变换(FPT)

本片题解设计两种解法

果然是签到题...

因为返回值问题T了好久...

第一眼：搜索大水题？

然后...竟然A了

 #include<cstdio>
 #include<queue>
 #include<iostream>
 #include<cstring>
 #define int long long
 using namespace std;
 inline int read(){
     int ans=,f=;char chr=getchar();
     while(!isdigit(chr)){if(chr=='-') f=-;chr=getchar();}
     while(isdigit(chr)){ans=(ans<<)+(ans<<)+chr-;chr=getchar();}
     return ans*f;
 }int fm,m,tot,a[],x,ff,p[],q[];
 void dfs(int x,int now){
     if(ff) return;
     if(x==&&now>=m) return;
     if(now<m){
         ff=;
         int t=;
         while(p[t]==) t--;
         cout<<t+<<endl<<now<<" ";
         for(int i=;i<=t;i++) cout<<p[i]<<" ";
         return;
     }
     int t=now/a[x];
     for(int i=t;i>=;i--)    p[x]=i,dfs(x-,now-a[x]*i);
 }
 signed main(){
     m=read(),fm=read();
     x=;a[]=;
     while(x<fm&&tot<=){a[++tot]=x*m;x=x*m;}
     dfs(tot,fm);
     return ;
 }

但其实只要分析一下，就发现式子跟进制转换有很大关系啊，我们只要把fm当做m进制数来处理即可

 #include<cstdio>
 #include<iostream>
 #include<cstring>
 #include<cmath>
 #include<algorithm>
 #include<cstdlib>
 #include<ctime>
 #define int long long
 using namespace std;
 inline int read(){
     int ans=,f=;char chr=getchar();
     while(!isdigit(chr)){if(chr=='-') f=-;chr=getchar();}
     while(isdigit(chr)){ans=(ans<<)+(ans<<)+chr-;chr=getchar();}
     return ans*f;
 }void write(long long x){
     if(x < ) putchar('-'),x = -x;
     if(x > ) write(x / );
     putchar(x %  + '');
 }int n,m,a[],tot;
 signed main(){
     m=read(),n=read();
     while(n){a[++tot]=n%m;n/=m;}
     printf("%d\n",tot);
     for(int i=;i<=tot;i++)write(a[i]),putchar(' ');
     return ;
 }