bnuoj 1071 拼图＋＋（BFS+康拓展开）

http://www.bnuoj.com/bnuoj/problem_show.php?pid=1071

【题意】：经过四个点的顺逆时针旋转，得到最终拼图

【题解】：康拓展开+BFS，注意先预处理，得到所有状态，然后用hash来调用存在的状态

【code】：

 #include <iostream>
 #include <stdio.h>
 #include <queue>
 #include <string.h>

 using namespace std;
 #define N 363000

 struct Nod
 {
     int b[];
     int pos;
 }nd1,nd2;

 int fac[] = {,,,,,,,,,};  //康拓展开用到的数组
  //康托展开：
 int cantor(int* a, int k)
 {
      int i, j, tmp, num = ;
      for (i = ; i < k; i++) {
          tmp = ;
          for (j = i + ; j < k; j++)
              if (a[j] < a[i])
                  tmp++;
          num += fac[k - i - ] * tmp;
      }
      return num;
 }

 int mark[N],pre[N];
 char dir[N];
 int cx[]={,,,};
 int cy[]={,,,};

 void exchange(int *a,int x,int y,int n)  //旋转
 {
     int temp;
     if(n%)
     {
         temp = a[*x+y];
         a[*x+y] = a[*x+y+];
         a[*x+y+] = a[*(x+)+y+];
         a[*(x+)+y+] = a[*(x+)+y];
         a[*(x+)+y] = temp;
     }
     else
     {
         temp = a[*(x+)+y];
         a[*(x+)+y] = a[*(x+)+y+];
         a[*(x+)+y+] = a[*x+y+];
         a[*x+y+] = a[*x+y];
         a[*x+y] = temp;
     }
 }

 void bfs(int *b)  //广度优先搜索
 {
     queue<Nod> q;
     memset(mark,,sizeof(mark));
     memset(pre,,sizeof(pre));
     memcpy(nd1.b,b,sizeof(int)*);
     int i,temp;
     temp = cantor(b,);
     mark[temp] = ;
     nd1.pos = temp;
     q.push(nd1);
     while(!q.empty())
     {
         nd2 = q.front();
         q.pop();
         for(i=;i<;i++)
         {
             memcpy(nd1.b,nd2.b,sizeof(int)*);
             exchange(nd1.b,cx[i/],cy[i/],i);
             temp = cantor(nd1.b,);
             if(mark[temp]!=)
             {
                 mark[temp] = ;
                 pre[temp] = pre[nd2.pos]+;
                 nd1.pos = temp;
                 q.push(nd1);
             }
         }
     }
 }

 int main()
 {
     char str[];
     int a[],b[]={,,,,,,,,},c[],hash[];
     bfs(b);
     int t;
     scanf("%d",&t);
     while(t--)
     {
         int i;
         for(i=;i<;i++)
         {
             scanf("%d",a+i);
             hash[a[i]] = i+; //hash
         }
         for(i=;i<;i++)
         {
             scanf("%d",c+i);
             c[i] = hash[c[i]];
         }
         int temp = cantor(c,);
         printf("Number Of Move(s) Needed: %d\n",pre[temp]);
     }
     return ;
 }