John's trip POJ

题意：

　　其实还是一个欧拉回路，但要按字典序走路；

解析：

　　我真是蠢啊emm。。。

　　map[i][j]表示由顶点i经街道j会到达的顶点编号

　　 然后枚举j就好了 用栈储存。。

虽然我不是这样写的

#include <iostream>
#include <cstdio>
#include <sstream>
#include <cstring>
#include <map>
#include <cctype>
#include <set>
#include <vector>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <bitset>
#define rap(i, a, n) for(int i=a; i<=n; i++)
#define rep(i, a, n) for(int i=a; i<n; i++)
#define lap(i, a, n) for(int i=n; i>=a; i--)
#define lep(i, a, n) for(int i=n; i>a; i--)
#define rd(a) scanf("%d", &a)
#define rlld(a) scanf("%lld", &a)
#define rc(a) scanf("%c", &a)
#define rs(a) scanf("%s", a)
#define pd(a) printf("%d
", a);
#define plld(a) printf("%lld
", a);
#define pc(a) printf("%c
", a);
#define ps(a) printf("%s
", a);
#define MOD 2018
#define LL long long
#define ULL unsigned long long
#define Pair pair<int, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define _  ios_base::sync_with_stdio(0),cin.tie(0)
//freopen("1.txt", "r", stdin);
using namespace std;
const int maxn = 10010, INF = 0x7fffffff, LL_INF = 0x7fffffffffffffff;

int deg[maxn], vis[maxn];
int way[50][maxn];
set<int> G[maxn];
stack<int> ss;

void dfs(int u)
{
    for(set<int>::iterator it = G[u].begin(); it != G[u].end(); it++)
    {
        int id = *it;
        int v = way[u][id];
        if(!vis[id])
        {
            vis[id] = 1;
            dfs(v);
            ss.push(id);
        }
    }
}

void fleury(int u)
{
    dfs(u);
}

void print()
{
    int sh = 0;
    while(!ss.empty())
    {
        if(sh++) cout << " ";
        cout << ss.top();
        ss.pop();
    }
    cout << endl;
}

int main()
{
    int u, v, id;
    while(scanf("%d%d", &u, &v) && u + v)
    {
        mem(deg, 0);
        mem(vis, 0);
        for(int i = 0; i < 50; i++) G[i].clear();
        mem(way, 0);
        int s = INF;
        cin >> id;
        way[u][id] = v;
        way[v][id] = u;
        G[u].insert(id);
        G[v].insert(id);
        s = min(s, u);
        s = min(s, v);
        deg[u]++;
        deg[v]++;
        while(scanf("%d%d", &u, &v) && u + v)
        {
            cin >> id;
            way[u][id] = v;
            way[v][id] = u;
            G[u].insert(id);
            G[v].insert(id);
            s = min(s, u);
            s = min(s, v);
            deg[u]++;
            deg[v]++;
        }
        int ans = 0;
        for(int i = 1; i <= 44; i++)
            if(deg[i] & 1) ans++;
        if(ans == 0)
        {
            fleury(s);
            print();
        }
        else
            cout << "Round trip does not exist." << endl;
    }

    return 0;
}