HDU Today---hdu2112（最短路-_-坑在是无向图）

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2112

spfa或者迪杰斯特拉都可以

注意公交车是有来回的---

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <cstring>
#include <map>
#include <string>
using namespace std;
#define INF 0xfffffff
#define N 12000
#define met(a, b) memset(a, b, sizeof(a))
typedef long long LL;

struct node
{
    int v, t;
    node(int v, int t):v(v), t(t){}
};

vector<vector<node> >G;

int s, e;
int cnt, vis[N], dist[N];

int spfa()
{
    met(vis, 0);
    for(int i=1; i<cnt; i++)
        dist[i] = INF;
    queue<int>Q;
    Q.push(s);
    vis[s] = 1;
    dist[s] = 0;

    while(Q.size())
    {
        int p = Q.front(); Q.pop();
        vis[p] = 0;
        int len = G[p].size(), q;
        for(int i=0; i<len; i++)
        {
            q = G[p][i].v;
            if( dist[q] > dist[p]+G[p][i].t )
            {
                dist[q] = dist[p]+G[p][i].t;
                if(vis[q] == 0)
                {
                    vis[q] = 1;
                    Q.push(q);
                }
            }
        }
    }
    return dist[e]==INF?-1:dist[e];
}
int main()
{
    int n;
    while(scanf("%d", &n), n!=-1)
    {
        map<string, int> M;
        M.clear();
        G.clear();
        G.resize(n*2+5);

        cnt = 1;

        char s1[50], s2[50];

        scanf("%s %s", s1, s2);

        if( !M[s1] ) M[s1]  = cnt++;
        if( !M[s2] ) M[s2]  = cnt++;

        s = M[s1];
        e = M[s2];

        for(int i=1; i<=n; i++)
        {
            int t, u, v;
            scanf("%s %s %d", s1, s2, &t);
            if(!M[s1]) M[s1]  = cnt++;
            if(!M[s2]) M[s2]  = cnt++;
            u = M[s1];
            v = M[s2];
            G[u].push_back(node(v, t));
            G[v].push_back(node(u, t));
        }

        printf("%d
", spfa());
    }
    return 0;
}