poj1041欧拉回路

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <algorithm>

#include <cmath>

#include <stack>

#include <queue>

#include <vector>

#include <map>

#include <string>

#include <iostream>

using namespace std;

const int maxn=2000;

int len;

int head[maxn];

struct Node

{

    int a;int b;int c;

}node[maxn];

struct edge

{

    int to;int val;int next;int op;int vis;

}e[maxn*maxn];



int add(int from,int to,int val)

{

    e[len].to=to;

    e[len].val=val;

    e[len].next=head[from];

    head[from]=len++;

    return len-1;

}

int n=0;

int sum;



int cmp(const Node &a,const Node &b)

{

    return a.c<b.c;

}

void dfs(int u)

{

    for(int i=head[u];i!=-1;i=e[i].next){

        if(!e[i].vis){

            e[i].vis=1;e[e[i].op].vis=1;

            int cc=e[i].to;

            dfs(cc);

            cout<<e[i].val<<" ";

        }

    }

}

int main()

{

    int a;int b;int c;

    int degree[maxn];

    while(scanf("%d%d",&a,&b),a||b){

        memset(degree,0,sizeof(degree));

        len=0;

        memset(head,-1,sizeof(head));

        sum=0;

        scanf("%d",&c); node[sum].a=a;node[sum].b=b;node[sum].c=c;

        sum++;if(a>n) n=a;if(b>n) b=n;

        while(scanf("%d%d",&a,&b),a||b){

            scanf("%d",&c);node[sum].a=a;node[sum].b=b;node[sum].c=c;

            sum++;if(a>n) n=a;if(b>n) n=b;

        }

        sort(node,node+sum,cmp);

        for(int i=0;i<sum;i++){

            int a=node[i].a;int b=node[i].b;int c=node[i].c;

            int cc=add(a,b,c);int cc1=add(b,a,c);

            degree[a]++;degree[b]++;

            e[cc].op=cc1;e[cc1].op=cc;

            e[cc].vis=e[cc1].vis=0;

        }

        int flag=0;

        for(int i=0;i<sum;i++){

            int a=node[i].a;int b=node[i].b;

            if((degree[a]&1)||(degree[b]&1)) {

                flag=1;break;

            }

        }

        if(!flag){

            dfs(1);

        }

        else

            cout<<"Round trip does not exist.";

        cout<<endl;

    }

    return 0;

}