POJ 3683 2-sat 算法

POJ 3683 2-sat 算法

  1  Source Code
  2  Problem:  3683         User: theorix
  3  Memory: 23864K        Time: 188MS
  4  Language: C ++         Result: Accepted
  5 
  6       *  Source Code
  7 
  8        #include < iostream >
  9        #include < algorithm >
 10         using   namespace  std;
 11         const   int  NN = 1009 ;
 12         int  visit[NN * 2 ];
 13         int   in [NN * 2 ];
 14         int  n;
 15         int  order[NN * 2 ],order_t;
 16         int  belong[NN * 2 ],belong_t;
 17         struct  seq
 18        {
 19             int  start,end;
 20        }v[NN * 2 ];
 21         struct  node
 22        {
 23             int  id;
 24            node  * next;
 25        }mem[ 5000000 ],path[NN * 2 ],rpath[NN * 2 ],way[NN * 2 ],way2[NN * 2 ];
 26         int  mem_t;
 27        inline  bool  cross( int  i, int  j)
 28        {
 29             if (v[i].start >= v[j].end || v[i].end <= v[j].start) return   false ;
 30             return   true ;
 31        }
 32        inline  void  link( int  i, int  j)
 33        {
 34            node * t =& mem[mem_t ++ ];
 35            t -> id = j;
 36            t -> next = path[i].next;
 37            path[i].next = t;
 38            t =& mem[mem_t ++ ];
 39            t -> id = i;
 40            t -> next = rpath[j].next;
 41            rpath[j].next = t;
 42        }
 43         void  dfs( int  k)
 44        {
 45            visit[k] = 1 ;
 46            node  * t;
 47             for (t = path[k].next;t;t = t -> next)
 48            {
 49                 if ( ! visit[t -> id])
 50                    dfs(t -> id);
 51            }
 52            order[ ++ order_t] = k;
 53        }
 54         void  rdfs( int  k)
 55        {
 56            visit[k] = 1 ;
 57            belong[k] = belong_t;
 58            node  * t;
 59             for (t = rpath[k].next;t;t = t -> next)
 60            {
 61                 if ( ! visit[t -> id])
 62                    rdfs(t -> id);
 63            }
 64        }
 65         bool  check()
 66        {
 67             int  i;
 68             for (i = 1 ;i <= n;i ++ )
 69                 if (belong[i * 2 - 1 ] == belong[i * 2 ])
 70                     return   false ;
 71             return    true ;
 72        }
 73         void  Dfs( int  k)
 74        {
 75            visit[k] = 2 ;
 76            node  * t;
 77             for (t = way[k].next;t;t = t -> next)
 78            {
 79                 if ( ! visit[t -> id])
 80                {
 81                    Dfs(t -> id);
 82                }
 83            }
 84        }
 85         void  display()
 86        {
 87             int  i,j;node  * t, * tt;
 88            memset( in , 0 , sizeof ( in ));
 89             for (i = 1 ;i <= 2 * n;i ++ )
 90            {
 91                 for (t = path[i].next;t;t = t -> next)
 92                {
 93                     int  a = belong[i],b = belong[t -> id];
 94                     if (a != b)
 95                    {
 96                         for (tt = way[b].next;tt;tt = tt -> next)
 97                        {
 98                             if (tt -> id == a) break ;
 99                        }
100                         if ( ! tt)
101                        {
102                            tt =& mem[mem_t ++ ];
103                            tt -> id = a;
104                            tt -> next = way[b].next;
105                            way[b].next = tt;
106                             in [a] ++ ;
107                        }
108                    }
109                }
110            }
111             for (i = 1 ;i <= n;i ++ )
112            {
113                 int  a = belong[i * 2 - 1 ],b = belong[i * 2 ];
114                 for (t = way2[b].next;t;t = t -> next)
115                     if (t -> id == a)
116                         break ;
117                 if ( ! t)
118                {
119                    tt =& mem[mem_t ++ ];
120                    tt -> id = a;
121                    tt -> next = way2[b].next;
122                    way2[b].next = tt;
123                }
124                 for (t = way2[a].next;t;t = t -> next)
125                     if (t -> id == b)
126                         break ;
127                 if ( ! t)
128                {
129                    tt =& mem[mem_t ++ ];
130                    tt -> id = b;
131                    tt -> next = way2[a].next;
132                    way2[a].next = tt;
133                }
134            }
135            memset(visit, 0 , sizeof (visit));
136            order_t = 0 ;
137             for (i = 1 ;i <= belong_t;i ++ )
138                 if ( in [i] == 0 )
139                    order[ ++ order_t] = i,visit[i] = 1 ;
140             int  q[NN * 2 ],qt = 0 ;
141             while (order_t >= 1 )
142            {
143                 int  tmp = order[order_t -- ];
144                q[ ++ qt] = tmp;
145                 for (t = way[tmp].next;t;t = t -> next)
146                     if ( ! visit[t -> id])
147                    {
148                         in [t -> id] -- ;
149                         if ( in [t -> id] == 0 )
150                            order[ ++ order_t] = t -> id,visit[t -> id] = 1 ;
151                    }
152            }
153            memset(visit, 0 , sizeof (visit));
154             for (i = 1 ;i <= qt;i ++ )
155            {
156                 if ( ! visit[q[i]])
157                {
158                    visit[q[i]] = 1 ;
159                     for (t = way2[q[i]].next;t;t = t -> next)
160                    {
161                         if ( ! visit[t -> id])
162                            Dfs(t -> id);
163                    }
164                }
165            }
166             for (i = 1 ;i <= n * 2 ;i ++ )
167                 if (visit[belong[i]] == 1 )
168                {
169                     int  start = v[i].start;
170                     int  end = v[i].end;
171                    printf( " %02d:%02d %02d:%02d\n " ,start / 60 ,start % 60 ,end / 60 ,end % 60 );
172                }
173        }
174         int  main()
175        {
176            mem_t = 0 ;
177            scanf( " %d " , & n);
178             int  i,j,k;
179             char  ch1[ 9 ],ch2[ 9 ];
180             int  t,tmp;
181             for (i = 1 ;i <= n;i ++ )
182            {
183                scanf( " %s%s%d " , & ch1, & ch2, & t);
184                v[ 2 * i - 1 ].start = atoi(ch1) * 60 + atoi(ch1 + 3 );
185                v[ 2 * i - 1 ].end = v[ 2 * i - 1 ].start + t;
186                v[ 2 * i].end = atoi(ch2) * 60 + atoi(ch2 + 3 );
187                v[ 2 * i].start = v[ 2 * i].end - t;
188            }
189             for (i = 1 ;i <= n;i ++ )
190            {
191                 for (j = i + 1 ;j <= n;j ++ )
192                {
193                     if (cross(i * 2 - 1 ,j * 2 - 1 ))
194                    {
195                        link(i * 2 - 1 ,j * 2 );
196                        link(j * 2 - 1 ,i * 2 );
197                    }
198                     if (cross(i * 2 - 1 ,j * 2 ))
199                    {
200                        link(i * 2 - 1 ,j * 2 - 1 );
201                        link(j * 2 ,i * 2 );
202                    }
203                     if (cross(i * 2 ,j * 2 - 1 ))
204                    {
205                        link(i * 2 ,j * 2 );
206                        link(j * 2 - 1 ,i * 2 - 1 );
207                    }
208                     if (cross(i * 2 ,j * 2 ))
209                    {
210                        link(i * 2 ,j * 2 - 1 );
211                        link(j * 2 ,i * 2 - 1 );
212                    }
213                }
214            }
215            memset(visit, 0 , sizeof (visit));
216            order_t = 0 ;
217             for (i = 1 ;i <= 2 * n;i ++ )
218            {
219                 if ( ! visit[i])
220                    dfs(i);
221            }
222            memset(visit, 0 , sizeof (visit));
223            belong_t = 0 ;
224             for (i = order_t;i >= 1 ;i -- )
225            {
226                 if ( ! visit[order[i]])
227                {
228                     ++ belong_t;
229                    rdfs(order[i]);
230                }
231            }
232             if ( ! check())
233                printf( " NO\n " );
234             else
235            {
236                printf( " YES\n " );
237                display();
238            }
239        }
240 
241