POJ 2387 Til the Cows Come Home

题目大意：

给你N个点 T条边， 求N->1的最短路

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
#define INF 0xfffffff
#define maxn 1002

struct Edge
{
    int e, w;
};

vector<Edge> G[1002];
bool vis[maxn];
int dist[maxn], n, m;;

void Init()
{
    for(int i=0; i<=n; i++)
    {
        G[i].clear();
        dist[i] = INF;
        vis[i] = false;
    }
}
int Spfa()
{
    Edge P, Pn;
    queue<Edge> Q;
    P.e = n, P.w = 0;
    dist[n] = 0;
    Q.push(P);

    while( !Q.empty() )
    {
        P = Q.front();
        Q.pop();

        vis[P.e] = false;
        int len = G[P.e].size();

        for(int i=0; i<len; i++)
        {
            Pn = G[P.e][i];

            if(dist[Pn.e] > dist[P.e] + Pn.w)
            {
                dist[Pn.e] = dist[P.e] + Pn.w;

                if( !vis[Pn.e] )
                {
                    Q.push(Pn);
                    vis[Pn.e] = true;
                }
            }
        }
    }
    return dist[1];
}
int main()
{
    Edge P;

    while(cin >> m >> n)
    {
        Init();
        for(int i=0; i<m; i++)
        {
            int a, b ,c;

            scanf("%d%d%d",&a,&b,&c);

            P.e = b, P.w = c;
            G[a].push_back(P);
            P.e = a;
            G[b].push_back(P);
        }

        int ans = Spfa();

        cout << ans << endl;
    }
    return 0;
}