poj1026Cipher(置换群）

链接

找循环节 然后所有子循环节的最小公倍数就是总的循环节 找结果的时候也按一个个置换来进行转换 不然也TLE

     #include <iostream>
     #include<cstdio>
     #include<string>
     #include<cstring>
     #include<algorithm>
     #include<stdlib.h>
     #include<map>
     using namespace std;
     #define LL long long
     int p[];
     char s[];
     char ss[],sq[];
     int vis[];
     int qu[][];
     int po[];
     int num[];
     LL gcd(int a,int b)
     {
         return b==?a:gcd(b,a%b);
     }
     int main()
     {
         int i,j,n;
         LL k;
         while(scanf("%d",&n)&&n)
         {
             memset(vis,,sizeof(vis));
             memset(num,,sizeof(num));
             for(i = ; i <= n ; i++)
             {
                 scanf("%d",&p[i]);
                 po[p[i]] = i;
             }
             LL sk = ;int g=;
             for(i =; i <= n ;i++)
             {
                 if(!vis[i])
                 {
                     vis[i] = ;
                     g++;
                     int x = i,o=;
                     qu[g][o] = i;
                     while()
                     {
                         x = p[x];
                         if(!vis[x])
                         {
                             vis[x] = ;
                         }
                         else
                         break;
                         o++;
                         qu[g][o] = x;
                     }
                     num[g] = o;
                     sk = sk/gcd(sk,o)*o;
                 }
             }
             while(scanf("%lld%*c",&k)&&k)
             {
                 gets(s);
                 int kk = strlen(s);
                 for(i = kk ; i < n ; i++)
                 s[i] = ' ';
                 s[n] = '\0';
                 strcpy(ss,s);
                 strcpy(sq,s);
                 k = k%sk;
                 for(i =  ; i <= g ; i++)
                 {
                     int kk = k%num[i];
                     strcpy(ss,sq);
                     while(kk)
                     {
                         for(j =  ; j <= num[i] ; j++)
                         s[qu[i][j]-] = ss[po[qu[i][j]]-];
                         strcpy(ss,s);
                         kk--;
                     }
                 }
                 puts(s);
             }
             puts("");
         }
         return ;
     }