[usaco3.3.1]fence

　　题目传送门：http://www.nocow.cn/index.php/Translate:USACO/fence
　　这道题直接模拟就好了

　　

/*
ID:abc31261
LANG:C++
TASK:fence
*/


#include<cstdio>
#include<cstring>
#include<vector>
#include<iostream>
using namespace std;
const int maxn=600,n=500;
vector<int> g[maxn];
int r[maxn],road[maxn],num=0,f[maxn][maxn];
void find(int x)
{
    int i,j;
    if (r[x]==0)
    {
        road[++num]=x;
        return;
    }
    for (i=1;i<=500;i++)
        if (f[x][i]!=0)
        {
            f[x][i]--; f[i][x]--;
            r[x]--;    r[i]--;
            find(i);
            
        }
    road[++num]=x;
}
int main()
{
    int m,i,j,l;
    freopen("fence.in","r",stdin);
    freopen("fence.out","w",stdout);
    scanf("%d",&m);
    memset(r,0,sizeof(r));
    for (i=1;i<=m;i++)
    {
        scanf("%d%d",&j,&l);
        f[j][l]++;
        f[l][j]++;
        r[l]++; r[j]++;
    }
    for (i=1;i<=n;i++)
        if (r[i]%2==1)
        {
            find(i);
            break;
        }
    if (num==0)find(1);
    for (i=num;i>=1;i--)cout<<road[i]<<endl;
    return 0;
}