建立精确覆盖模型求解（Dancing Links）~

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  1 #include <cstdio>
  2 #include <cstring>
  3 #include <algorithm>
  4 
  5  using namespace std;
  6 
  7  const int MAXR = 1024;
  8 const int MAXC = 512;
  9 const int SIZE = 1024;
 10 const int INF = (1 << 20);
 11 
 12 struct Node
 13 {
 14     Node * u;
 15     Node * d;
 16     Node * l;
 17     Node * r;
 18     int rnum;
 19     int cnum;
 20 };
 21 
 22 int node;
 23 int sum[MAXC];
 24 Node head;
 25 Node row[MAXR];
 26 Node column[MAXC];
 27 Node pool[MAXR * MAXC];
 28 
 29 int alen;
 30 int ans[MAXR];
 31 
 32 void InitDLX(int nr,int nc)
 33 {
 34     node = 0;
 35     memset(sum,0,sizeof(sum));
 36     head.r = &column[0];
 37     column[0].cnum = 0;
 38     column[0].l = &head;
 39     column[0].u = column[0].d = &column[0];
 40     for (int i = 1; i < nc; i++)
 41     {
 42         column[i].cnum = i;
 43         column[i-1].r = &column[i];
 44         column[i].l = &column[i-1];
 45         column[i].u = column[i].d = &column[i];
 46     }
 47     column[nc-1].r = &head;
 48     head.l = &column[nc-1];
 49 
 50     for (int i = 0; i < nr; i++)
 51         row[i].l = row[i].r = &row[i];
 52 }
 53 
 54 void InsertDLX(int r,int c)
 55 {
 56     sum[c]++;
 57     pool[node].rnum = r;
 58     pool[node].cnum = c;
 59     pool[node].l = row[r].l;
 60     pool[node].r = &row[r];
 61     row[r].l->r = &pool[node];
 62     row[r].l = &pool[node];
 63     pool[node].u = column[c].u;
 64     pool[node].d = &column[c];
 65     column[c].u->d = &pool[node];
 66     column[c].u = &pool[node];
 67 
 68     node++;
 69 }
 70 
 71 void DeleteRowHeadDLX(int nr)
 72 {
 73     for (int i = 0; i < nr; i++)
 74     {
 75         row[i].l->r = row[i].r;
 76         row[i].r->l = row[i].l;
 77     }
 78 }
 79 
 80 void RemoveColumn(Node * col)
 81 {
 82     col->l->r = col->r;
 83     col->r->l = col->l;
 84     for (Node * p = col->d; p != col; p = p->d)
 85         for (Node * q = p->r; q != p; q = q->r)
 86         {
 87             q->u->d = q->d;
 88             q->d->u = q->u;
 89             sum[q->cnum]--;
 90         }
 91 }
 92 
 93 void ResumeColumn(Node * col)
 94 {
 95     col->l->r = col;
 96     col->r->l = col;
 97     for (Node * p = col->d; p != col; p = p->d)
 98         for (Node * q = p->r; q != p; q = q->r)
 99         {
100             q->u->d = q;
101             q->d->u = q;
102             sum[q->cnum]++;
103         }
104 }
105 
106 bool dfs(int k)
107 {
108     if (head.r == &head)
109     {
110         alen = k;
111         return true;
112     }
113 
114     int minl = INF;
115     Node * mincol;
116     for (Node * p = head.r; p != &head; p = p->r)
117         if (sum[p->cnum] < minl)
118         {
119             minl = sum[p->cnum];
120             mincol = p;
121         }
122     RemoveColumn(mincol);
123     for (Node * p = mincol->d; p != mincol; p = p->d)
124     {
125         for (Node * q = p->r; q != p; q = q->r)
126             RemoveColumn(&column[q->cnum]);
127         if (dfs(k + 1))
128         {
129             ans[k] = p->rnum;
130             return true;
131         }
132         for (Node * q = p->l; q != p; q = q->l)
133             ResumeColumn(&column[q->cnum]);
134     }
135     ResumeColumn(mincol);
136     return false;
137 }
138 
139 bool gmap[SIZE][SIZE];
140 
141 int lable[SIZE];
142 
143 int main()
144 {
145     int nv;
146     int ne;
147     int nd;
148 
149     int nr;
150     int nc;
151 
152     int u;
153     int v;
154     int o;
155 
156     while(scanf("%d %d %d",&nv,&ne,&nd) != EOF)
157     {
158         nr = 0;
159         nc = nv + nd * nv;
160         memset(gmap,false,sizeof(gmap));
161 
162         for(int i = 0; i < ne; i++)
163         {
164             scanf("%d %d",&u,&v);
165             gmap[u - 1][v - 1] = gmap[v - 1][u - 1] = true;
166         }
167 
168         for(int i = 0; i < nv; i++)
169             gmap[i][i] = true;
170 
171         for(int i = 0; i < nv; i++)
172         {
173             scanf("%d %d",&u,&v);
174 
175             u--;
176             v--;
177 
178             for(int s = u; s <= v; s++)
179                 for(int e = s; e <= v; e++)
180                     lable[nr++] = i * 100 + s * 10 + e;
181 
182             lable[nr++] = i * 100 + nd * 10 + nd;
183         }
184 
185         InitDLX(nr,nc);
186 
187         for(int i = 0; i < nr; i++)
188         {
189             o = lable[i] / 100;
190             u = (lable[i] % 100) / 10;
191             v = lable[i] % 10;
192 
193             InsertDLX(i,o);
194 
195             if(u == nd && v == nd) continue;
196 
197             for(int j = 0; j < nv; j++)
198                 if(gmap[o][j])
199                     for(int k = u; k <= v; k++)
200                         InsertDLX(i,nv + j * nd + k);
201         }
202 
203         DeleteRowHeadDLX(nr);
204 
205         if(!dfs(0)) printf("No solution\n");
206         else
207         {
208             sort(ans,ans + alen);
209             for(int i = 0; i < alen; i++)
210             {
211                 u = (lable[ans[i]] % 100) / 10;
212                 v = lable[ans[i]] % 10;
213                 if(u == nd && v == nd) printf("0 0\n");
214                 else printf("%d %d\n",u + 1,v + 1);
215             }
216         }
217         printf("\n");
218     }
219     return 0;
220 }