[U]3.3.1 欧拉回路

欧拉回路，采用递归的方法。采用递归的方法实现。

/*
ID:bysen
LANG:C++
PROG:fence
*/
#include<stdio.h>
#include<stack>
#define MAXN 501
#define MAXF 1025
using namespace std;

int map[MAXN][MAXN]={0};
int circuit[MAXF];
int nodenum;
int maxnode=0;
int degree[MAXN]={0};
int N;

int max( int a,int b ){ return a>b?a:b; }

void work(int start)
{
 	 bool found=false;
 	 for( int i=1;i<=maxnode;i++ )
 	 {
	  	  if( map[start][i] )
	  	  {
		   	  map[start][i]--;
		   	  map[i][start]--;
		   	  work(i);
		   	  found=true;
 		  }
	 }
	 circuit[nodenum++]=start;
}

int main()
{
 	freopen( "fence.in","r",stdin );
 	freopen( "fence.out","w",stdout );
 	scanf( "%d",&N );
 	for( int i=1;i<=N;i++ )
 	{
	 	 int u,v;
	 	 scanf( "%d %d",&u,&v );
	 	 maxnode=max(maxnode,u);
	 	 maxnode=max(maxnode,v);
	 	 degree[u]++;
	 	 degree[v]++;
	 	 map[u][v]++;
		 map[v][u]++;
	}
	int start;
	for( int i=1;i<=maxnode;i++ )
		 if( degree[i]%2==1 )
		 {
		 	 start=i;
		 	 break;
		 }
    degree[start]--;
	work(start);
	for( int i=nodenum-1;i>=0;i-- )
		 printf( "%d\n",circuit[i] );
 	return 0;
}