HDU 1054 Strategic Game (min-dot overlay on binary chart)

Strategic Game

Time limit:20000/10000 MS (java/others) Memory limit:65536/32768 K (java/others)

DescriptionBob enjoys playing computer games, especially strategic games, but sometimes he cannot find the solution fast enough and T Hen he is very sad. Now he has the following problem. He must defend a medieval city, the roads of which form a tree. He has to put the minimum number of soldiers in the nodes so, they can observe all the edges. Can you help him?

Your program should find the minimum number of soldiers that Bob have to put for a given tree.

The input file contains several data sets in text format. Each data set represents a tree with the following description:

The number of nodes
The description of each node in the following format
Node_identifier: (number_of_roads) node_identifier1 node_identifier2 ... node_identifier
Or
Node_identifier: (0)

The node identifiers is integer numbers between 0 and n-1, for n nodes (0 < n <= 1500). Every edge appears only once in the input data.

For example for the tree:



The solution is a soldier (at the Node 1).

The output should is printed on the standard output. For each given input data set, print one, integer number in a, gives the result (the minimum number of sold Iers). An example are given in the following table:

Sample Input40: (1) 11: (2) 2 32: (0) 3: (0) 53: (3) 1 4 21: (1) 02: (0) 0: (0) 4: (0) Sample Output1 2 Test instructions: Give you a tree, each node needs to be guarded by soldiers, a soldier can watch his node and node adjacent to the node, asked how many soldiers to see all the nodes Analysis: The minimum point overlay of a binary graph is the maximum match. Because the points are more, the adjacency matrix form of the Hungarian algorithm will time out, and the adjacency table will be used. Of course, you can also use the HOPCROFT-CARP algorithm

#include <stdio.h>#include<string.h>#include<iostream>using namespacestd;Const intMAXN = -;structedge{intTo,next;} EDGE[MAXN*2];intHead[maxn],tol;intN;intLINKER[MAXN];BOOLUSED[MAXN];voidinit () {tol=0; memset (Head,-1,sizeof(head));}voidAddedge (intUintv) {edge[tol].to=v; Edge[tol].next=Head[u]; Head[u]=tol++;}BOOLDfsintu) {     for(inti=head[u];i!=-1; i=Edge[i].next) {        intv=edge[i].to; if(!Used[v]) {Used[v]=true; if(linker[v]==-1||DFS (Linker[v])) {Linker[v]=T; return true; }        }    }    return false;}intHungary () {intres=0; MEMSET (linker,-1,sizeof(linker));  for(intu=0; u<n;u++) {memset (used,false,sizeof(used)); if(Dfs (U)) res++; }    returnRes;}intMain () {intu,v,t;  while(SCANF ("%d", &n) = =1&&N) {init ();  for(u=0; u<n;u++) {scanf ("%d: (%d)",&u,&t);  for(intI=1; i<=t;i++) {scanf ("%d",&v);                Addedge (U,V);            Addedge (V,u); }} printf ("%d\n", Hungary ()/2); }    return 0;}

HDU 1054 Strategic Game (min-dot overlay on binary chart)