Again Prime? No Time. UVA - 10780

给定 m,n ，求最大的 k 使得 m^k∣n!

 

分解质因数

 

 

 

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#include <iostream> #include <cstring> #include <sstream> using namespace std; const int N =1e4+20; const int inf =1e9 ;  int n,m,a[N],b[N];  int prime[N],tot,vis[N];     void init(int top){     for(int i=2;i<=top;++i)         if(vis[i]==0){             prime[++tot]=i;             for(int j=i*2;j<=top;j+=i) vis[j]=1;         }    }  void sov(int cas){     int i ;     memset(a,0,sizeof a);memset(b,0,sizeof b);     cin>>m>>n;     for(i=1;i<=tot;i++){         if(m%prime[i]==0){             while(m%prime[i]==0)                 a[i]++,m/=prime[i];         }     }     for(i=1;i<=tot;i++){         int t=n;         while(t){             b[i]+=(t/prime[i]);             t/=prime[i];         }     }     int ans=inf;     for(i=1;i<=tot;i++){         if(a[i])             ans=min(ans,b[i]/a[i]);     }     if(ans==0)printf("Case %d:\nImpossible to divide\n",cas);     else printf("Case %d:\n%lld\n",cas,ans);  }  signed main(){     init(1e4);     int tes,cas=0;cin>>tes;     while(tes--) sov(++cas);  }