[HDOJ3526]Computer Assembling

最小割应用~

#include <cstdio>
  2 #include <cstring>
  3 
  4  constint INF = (1<<30);
  5 
  6 class Network
  7 {
  8 private:
  9 conststaticint MAXV =512; // 顶点数
 10 conststaticint MAXE =512000; // 边数 * 2
 11 
 12 struct List
 13     {
 14 int v;
 15 int f;
 16         List * rev;
 17         List * next;
 18     };
 19 
 20     List pool[MAXE];
 21     List * path[MAXV];
 22     List * head[MAXV];
 23     List * cur[MAXV];
 24     List * pp;
 25 
 26 int n;
 27 int s;
 28 int t;
 29 int dist[MAXV];
 30 int num[MAXV];
 31 int pred[MAXV];
 32 
 33     inline List * create(int v,int f,List * next)
 34     {
 35         pp->v = v;
 36         pp->f = f;
 37         pp->next = next;
 38 return pp++;
 39     }
 40 
 41 void InitDist();
 42 void Augment(int&);
 43 public:
 44 void Init(int nv,int ss,int tt);
 45 void addEdge(int u,int v,int f);
 46 int maxFlow();
 47 };
 48 
 49 void Network::Init(int nv,int ss,int tt)
 50 {
 51     n = nv;
 52     s = ss;
 53     t = tt;
 54 
 55     pp = pool;
 56     memset(head,0,n *sizeof(head[0]));
 57     memset(cur,0,n *sizeof(cur[0]));
 58     memset(num,0,n *sizeof(int));
 59 
 60     pred[s] =-1;
 61 
 62 for (int i =0;i < n;i++)
 63         dist[i] = n;
 64 
 65 return;
 66 }
 67 
 68 void Network::addEdge(int u,int v,int f)
 69 {
 70     head[u] = create(v,f,head[u]);
 71     head[v] = create(u,0,head[v]);
 72 
 73     head[u]->rev = head[v];
 74     head[v]->rev = head[u];
 75 
 76 return;
 77 }
 78 
 79 void Network::InitDist()
 80 {
 81 int queue[MAXV];
 82 int qh =-1;
 83 int qe =0;
 84 
 85     dist[t] =0;
 86     queue[0] = t;
 87 
 88 while (qh != qe)
 89     {
 90         qh++;
 91 int u = queue[qh];
 92 for (List * p = head[u];p;p = p->next)
 93 if (p->f ==0&& dist[p->v] == n)
 94             {
 95                 dist[p->v] = dist[u] +1;
 96                 num[dist[p->v]]++;
 97                 queue[++qe] = p->v;
 98             }
 99     }
100 
101 return;
102 }
103 
104 void Network::Augment(int& sum)
105 {
106 int minl = INF;
107 for (int u = t;u != s;u = pred[u])
108         minl = minl < path[u]->f ? minl : path[u]->f;
109     sum += minl;
110 for (int u = t;u != s;u = pred[u])
111     {
112         path[u]->f -= minl;
113         path[u]->rev->f += minl;
114     }
115 
116 return;
117 }
118 
119 int Network::maxFlow()
120 {
121 bool update;
122 int u = s;
123 int ret =0;
124 
125     InitDist();
126 for (int i =0;i < n;i++)
127         cur[i] = head[i];
128 
129 while (dist[s] < n)
130     {
131         update =false;
132 for (List * p = cur[u];p;p = p->next)
133 if (dist[p->v] +1== dist[u] && p->f >0)
134             {
135                 update =true;
136                 pred[p->v] = u;
137                 path[p->v] = p;
138                 cur[u] = p;
139                 u = p->v;       // 前进步
140 if (u == t)
141                 {
142                     Augment(ret);
143                     u = s;
144                 }
145 break;
146             }
147 if (!update)
148         {
149 if ( --num[dist[u]] ==0)   // 间隙优化
150 break;
151             cur[u] = head[u];
152             dist[u] = n;
153 for (List * p = head[u];p;p = p->next)      // 重标号
154 if (p->f >0&& dist[u] > dist[p->v] +1)
155                     dist[u] = dist[p->v] +1;
156 if (dist[u] < n)
157                 num[dist[u]]++;
158 if (u != s)                         // 回退步
159                 u = pred[u];
160         }
161     }
162 return ret;
163 }
164 
165 Network net;
166 
167 int main()
168 {
169 int nd;
170 int nw;
171 int u;
172 int v;
173 int val;
174 
175 while(scanf("%d %d",&nd,&nw) != EOF)
176     {
177         net.Init(nd +2,0,nd +1);
178 
179 for(int i =1;i <= nd;i++)
180         {
181             scanf("%d",&val);
182             net.addEdge(0,i,val);
183         }
184 
185 for(int i =1;i <= nd;i++)
186         {
187             scanf("%d",&val);
188             net.addEdge(i,nd +1,val);
189         }
190 
191 for(int i =0;i < nw;i++)
192         {
193             scanf("%d %d %d",&u,&v,&val);
194             net.addEdge(u,v,val);
195             net.addEdge(v,u,val);
196         }
197 
198         printf("%d\n",net.maxFlow());
199     }
200 return0;
201 }