1 #include<cstdio> 2 #define INF 0x7FFFFFFF 3 #define MAXN 1000010 4 int n, m, size; 5 int L[MAXN], R[MAXN], U[MAXN], D[MAXN], H[MAXN]; 6 int S[MAXN], C[MAXN], X[MAXN], Q[MAXN]; 7 void Init() { 8 int i; 9 for (i = 0; i <= m; i++) { 10 S[i] = 0; 11 L[i + 1] = i; 12 R[i] = i + 1; 13 U[i] = D[i] = i; 14 } 15 R[m] = 0; 16 size = m + 1; 17 } 18 void Remove(int c) { 19 int i, j; 20 R[L[c]] = R[c]; 21 L[R[c]] = L[c]; 22 for (i = D[c]; i != c; i = D[i]) { 23 for (j = R[i]; j != i; j = R[j]) { 24 D[U[j]] = D[j]; 25 U[D[j]] = U[j]; 26 S[C[j]]--; 27 } 28 } 29 } 30 void Resume(int c) { 31 int i, j; 32 R[L[c]] = c; 33 L[R[c]] = c; 34 for (i = D[c]; i != c; i = D[i]) { 35 for (j = R[i]; j != i; j = R[j]) { 36 U[D[j]] = j; 37 D[U[j]] = j; 38 S[C[j]]++; 39 } 40 } 41 } 42 void Link(int r, int c) { 43 S[c]++; 44 D[size] = D[c]; 45 U[size] = c; 46 U[D[c]] = size; 47 D[c] = size; 48 if (H[r] < 0) 49 H[r] = L[size] = R[size] = size; 50 else { 51 L[size] = H[r]; 52 R[size] = R[H[r]]; 53 L[R[H[r]]] = size; 54 R[H[r]] = size; 55 } 56 C[size] = c; 57 X[size++] = r; 58 } 59 bool Dance(int now) { 60 int i, j, c, temp; 61 if (R[0] == 0) { 62 printf("%d", now); 63 for (i = 0; i < now; i++) 64 printf(" %d", X[Q[i]]); 65 putchar('\n'); 66 return true; 67 } 68 for (temp = INF, i = R[0]; i; i = R[i]) { 69 if (S[i] < temp) { 70 c = i; 71 temp = S[i]; 72 } 73 } 74 Remove(c); 75 for (i = D[c]; i != c; i = D[i]) { 76 Q[now] = i; 77 for (j = R[i]; j != i; j = R[j]) 78 Remove(C[j]); 79 if (Dance(now + 1)) 80 return true; 81 for (j = L[i]; j != i; j = L[j]) 82 Resume(C[j]); 83 } 84 Resume(c); 85 return false; 86 } 87 int main() { 88 int i, j, k; 89 while (~scanf("%d%d", &n, &m)) { 90 Init(); 91 for (i = 1; i <= n; i++) { 92 H[i] = -1; 93 scanf("%d", &k); 94 while (k--) { 95 scanf("%d", &j); 96 Link(i, j); 97 } 98 } 99 if (!Dance(0)) 100 puts("NO"); 101 } 102 return 0; 103 }
