题目链接：http://acm.sgu.ru/problem.php?contest=0&problem=223
题意：n*n个格子里放k个王（走相邻8个格子），问不互相碰到的放法一共多少个。
状压dp，设dp(st,i,r)为到第i行，st状态，并且目前为止已经放了r个的所有情况。
转移为dp(cur,i,r)=∑dp(pre,i-1,r-x)，x为cur的1的数量，r枚举的范围是[x,k]。
1 /* 2 ━━━━━┒ギリギリ♂ eye！ 3 ┓┏┓┏┓┃キリキリ♂ mind！ 4 ┛┗┛┗┛┃＼○／ 5 ┓┏┓┏┓┃ / 6 ┛┗┛┗┛┃ノ) 7 ┓┏┓┏┓┃ 8 ┛┗┛┗┛┃ 9 ┓┏┓┏┓┃ 10 ┛┗┛┗┛┃ 11 ┓┏┓┏┓┃ 12 ┛┗┛┗┛┃ 13 ┓┏┓┏┓┃ 14 ┃┃┃┃┃┃ 15 ┻┻┻┻┻┻ 16 */ 17 #include <algorithm> 18 #include <iostream> 19 #include <iomanip> 20 #include <cstring> 21 #include <climits> 22 #include <complex> 23 #include <cassert> 24 #include <cstdio> 25 #include <bitset> 26 #include <vector> 27 #include <deque> 28 #include <queue> 29 #include <stack> 30 #include <ctime> 31 #include <set> 32 #include <map> 33 #include <cmath> 34 using namespace std; 35 #define fr first 36 #define sc second 37 #define cl clear 38 #define BUG puts("here!!!") 39 #define W(a) while(a--) 40 #define pb(a) push_back(a) 41 #define Rint(a) scanf("%d", &a) 42 #define Rs(a) scanf("%s", a) 43 #define FRead() freopen("in", "r", stdin) 44 #define FWrite() freopen("out", "w", stdout) 45 #define Rep(i, len) for(int i = 0; i < (len); i++) 46 #define For(i, a, len) for(int i = (a); i < (len); i++) 47 #define Cls(a) memset((a), 0, sizeof(a)) 48 #define Clr(a, x) memset((a), (x), sizeof(a)) 49 #define Full(a) memset((a), 0x7f7f7f, sizeof(a)) 50 #define lrt rt << 1 51 #define rrt rt << 1 | 1 52 #define pi 3.14159265359 53 #define RT return 54 #define lowbit(x) x & (-x) 55 #define onenum(x) __builtin_popcount(x) 56 typedef long long LL; 57 typedef long double LD; 58 typedef unsigned long long ULL; 59 typedef pair<int, int> pii; 60 typedef pair<string, int> psi; 61 typedef pair<LL, LL> pll; 62 typedef map<string, int> msi; 63 typedef vector<int> vi; 64 typedef vector<LL> vl; 65 typedef vector<vl> vvl; 66 typedef vector<bool> vb; 67 68 const int maxn = 12; 69 LL dp[1<<maxn][maxn][maxn*maxn]; 70 int n, k; 71 72 bool ok(LL x, LL y) { 73 if(x & y) return 0; 74 if((x << 1) & y) return 0; 75 if((x >> 1) & y) return 0; 76 return 1; 77 } 78 79 bool line(LL x) { 80 if((x >> 1) & x) return 0; 81 return 1; 82 } 83 84 signed main() { 85 // FRead(); 86 while(~scanf("%d%d",&n,&k)) { 87 LL nn = 1 << n; 88 Cls(dp); 89 Rep(st, nn) { 90 if(line(st)) { 91 dp[st][1][__builtin_popcount(st)] = 1; 92 } 93 } 94 For(i, 2, n+1) { 95 Rep(cur, nn) { 96 if(!line(cur)) continue; 97 LL x = __builtin_popcount(cur); 98 Rep(pre, nn) { 99 if(!line(pre)) continue; 100 For(r, x, k+1) { 101 if(ok(cur, pre)) { 102 dp[cur][i][r] += dp[pre][i-1][r-x]; 103 } 104 } 105 } 106 } 107 } 108 LL ret = 0; 109 Rep(i, nn) ret += dp[i][n][k]; 110 cout << ret << endl; 111 } 112 RT 0; 113 }