HDU 1068 Girls and Boys (the largest independent set of two graphs)

Title Link: http://acm.hdu.edu.cn/showproblem.php?pid=1068

There are n classmates, the format ni: (m) N1 n2 N3 said classmate Ni destined and n1,n2,n3 become a couple, ask the collection does not exist in the first couple of classmates the biggest classmate number.

Independent set (a subset of the vertex sets of the graph, where any two points are not adjacent)

Maximum independent set = vertex number-Maximum match number in a binary graph

Because men and women do not know, to split a person into two gender, the maximum match, divided by 2 on the line.

This approach is more difficult to understand.

1#include <iostream>2#include <cstdio>3#include <cstring>4 using namespacestd;5 Const intN = 1e3 +5;6 structEdge {7     intnext, to;8}edge[n *N];9 intHead[n], CNT;Ten intMatch[n]; One BOOLVis[n]; A  - voidinit () { -Memset (Head,-1,sizeof(head)); thememset (Match,-1,sizeof(Match)); -memset (Vis,false,sizeof(Vis)); -CNT =0; - } +  -InlinevoidAddintU,intv) { +Edge[cnt].next =Head[u]; AEdge[cnt].to =v; atHead[u] = cnt++; - } -  - BOOLDfsintu) { -      for(inti = Head[u]; ~i; i =Edge[i].next) { -         intv =edge[i].to; in         if(!Vis[v]) { -VIS[V] =true; to             if(Match[v] = =-1||DFS (Match[v])) { +MATCH[V] =u; -                 return true; the             } *         } $     }Panax Notoginseng     return false; - } the  + intHungry (intN) { A     intres =0; the      for(inti =0; I < n; ++i) { +memset (Vis,false,sizeof(Vis)); -         if(Dfs (i)) $res++; $     } -     returnRes; - } the  - intMain ()Wuyi { the     intN; -      while(~SCANF ("%d", &N)) { Wu init (); -         intv; About          for(inti =0; I < n; ++i) { $             intnum1, num; -scanf"%d: (%d)", &AMP;NUM1, &num); -              while(num--) { -scanf"%d", &v); A Add (i, v); +             } the         } -printf"%d\n", N-hungry (n)/2); $     } the     return 0; the}

HDU 1068 Girls and Boys (the largest independent set of two graphs)