题解：从中心出发，减到边就算一种，两个方向反向减，关于两点的 位置中心对称
AC代码如下：
#include<iostream> #include<algorithm> #include<cstring> using namespace std; int book[8][8],nex1[4][2]={0,1,1,0,0,-1,-1,0},nex2[4][2]={0,-1,-1,0,0,1,1,0},cnt; bool judge(int x,int y) { if(x<=0||x>=6||y<=0||y>=6) return true; return false; } void dfs(int x,int y,int nx,int ny) { if(judge(x,y)) { cnt++; return ; } int i,xiax,xiay,a,b; for(i=0;i<4;i++) { xiax=x+nex1[i][0]; xiay=y+nex1[i][1]; a=nx+nex2[i][0]; b=ny+nex2[i][1]; if(book[xiax][xiay]==0 && book[a][b]==0) { book[xiax][xiay]=1; book[a][b]=1; dfs(xiax,xiay,a,b); book[xiax][xiay]=0; book[a][b]=0; } } return ; } int main() { memset(book,0,sizeof(book)); cnt=0; book[3][3]=1; dfs(3,3,3,3); cout<<cnt/4<<endl; }answer:509