【HDU】3498 whosyourdaddy

  1 #include<cstdio>

  2 #include<cstring>

  3 #include<algorithm>

  4 #define MAXN 10000

  5 #define MAXM 60

  6 #define INF 0x7FFFFFFF

  7 using namespace std;

  8 bool G[MAXM][MAXM];

  9 int R[MAXN], L[MAXN], U[MAXN], D[MAXN];

 10 int size, ans, C[MAXN], S[MAXN], H[MAXN];

 11 bool vis[MAXM];

 12 void Init(int n)

 13 {

 14     int i;

 15     memset(G, false, sizeof(G));

 16     for (i = 0; i <= n; i++)

 17     {

 18         R[i] = i + 1;

 19         L[i + 1] = i;

 20         U[i] = D[i] = i;

 21         S[i] = 0;

 22         H[i] = -1;

 23     }

 24     R[n] = 0;

 25     size = n + 1;

 26 }

 27 void Link(int r, int c)

 28 {

 29     U[size] = c;

 30     D[size] = D[c];

 31     U[D[c]] = size;

 32     D[c] = size;

 33     if (H[r] < 0)

 34         H[r] = L[size] = R[size] = size;

 35     else

 36     {

 37         L[size] = H[r];

 38         R[size] = R[H[r]];

 39         L[R[H[r]]] = size;

 40         R[H[r]] = size;

 41     }

 42     S[c]++;

 43     C[size++] = c;

 44 }

 45 void Remove(int c)

 46 {

 47     int i;

 48     for (i = D[c]; i != c; i = D[i])

 49     {

 50         L[R[i]] = L[i];

 51         R[L[i]] = R[i];

 52     }

 53 }

 54 void Resume(int c)

 55 {

 56     int i;

 57     for (i = D[c]; i != c; i = D[i])

 58         L[R[i]] = R[L[i]] = i;

 59 }

 60 int A()

 61 {

 62     int i, j, k, res;

 63     memset(vis, false, sizeof(vis));

 64     for (res = 0, i = R[0]; i; i = R[i])

 65     {

 66         if (!vis[i])

 67         {

 68             res++;

 69             for (j = D[i]; j != i; j = D[j])

 70             {

 71                 for (k = R[j]; k != j; k = R[k])

 72                     vis[C[k]] = true;

 73             }

 74         }

 75     }

 76     return res;

 77 }

 78 void Dance(int now)

 79 {

 80     if (R[0] == 0)

 81         ans = min(ans, now);

 82     else if (now + A() < ans)

 83     {

 84         int i, j, temp, c;

 85         for (temp = INF,i = R[0]; i; i = R[i])

 86         {

 87             if (temp > S[i])

 88             {

 89                 temp = S[i];

 90                 c = i;

 91             }

 92         }

 93         for (i = D[c]; i != c; i = D[i])

 94         {

 95             Remove(i);

 96             for (j = R[i]; j != i; j = R[j])

 97                 Remove(j);

 98             Dance(now + 1);

 99             for (j = L[i]; j != i; j = L[j])

100                 Resume(j);

101             Resume(i);

102         }

103     }

104 }

105 int main()

106 {

107     int n, m, u, v, i, j;

108     while (~scanf("%d%d", &n, &m))

109     {

110         Init(n);

111         while (m--)

112         {

113             scanf("%d%d", &u, &v);

114             G[u][v] = G[v][u] = true;

115         }

116         for (i = 1; i <= n; i++)

117         {

118             G[i][i] = true;

119             for (j = 1; j <= n; j++)

120             {

121                 if (G[i][j])

122                     Link(i, j);

123             }

124         }

125         ans = INF;

126         Dance(0);

127         printf("%d\n", ans);

128     }

129     return 0;

130 }