UVA 10986 Sending email 最短路问题

基本的最短路问题 就是数据需要稍微处理一下。（N比较大）dijkstra也要优化。不优化应该会T；

#include <map>

#include <set>

#include <list>

#include <cmath>

#include <ctime>

#include <deque>

#include <stack>

#include <queue>

#include <cctype>

#include <cstdio>

#include <string>

#include <vector>

#include <climits>

#include <cstdlib>

#include <cstring>

#include <iostream>

#include <algorithm>

#define LL long long

#define PI 3.1415926535897932626

using namespace std;

int gcd(int a, int b) {return a % b ==  ? b : gcd(b, a % b);}

int N,M,S,T;

const int INF = 0x3f3f3f3f;

typedef pair<int,int> pii;

#define MAXN 20005

priority_queue<pii,vector<pii>,greater<pii> >q;

struct node

{

    int v;

    int w;

};

vector <node>G[MAXN];//G[u].v = w present dis[u][v] = w;

int d[MAXN];

void read()

{

    scanf("%d%d%d%d",&N,&M,&S,&T);

    for (int i = ; i <= N; i++)G[i].clear();

    while (M--)

    {

        int u,v,w;

        scanf("%d%d%d",&u,&v,&w);

        node tmp; tmp.v = v; tmp.w = w;

        G[u].push_back(tmp);

        tmp.v = u; tmp.w = w;

        G[v].push_back(tmp);

    }

}

void dijkstra(int st)

{

    memset(d,0x3f,sizeof(d));

    d[st] = ;

   // printf("%d\n",st);

    while (!q.empty()) q.pop();

    q.push(make_pair(d[st],st));

    while (!q.empty())

    {

        pii u = q.top(); q.pop();

        int x = u.second;

        if (u.first != d[x]) continue;

        for (int i = ; i < (int)G[x].size(); i++)

        {

            int v = G[x][i].v, w = G[x][i].w;

            //printf("%d %d\n",v,w);

            if (d[v] > d[x] + w)

            {

                d[v] = d[x] + w;

                //printf("%d %d\n",d[v],v);

                q.push(make_pair(d[v],v));

            }

        }

    }

}

int main()

{

    int num, kase = ;

    scanf("%d",&num);

    while (num--)

    {

        read();

        dijkstra(S);

        if (d[T] == INF) printf("Case #%d: unreachable\n",kase++);

        else printf("Case #%d: %d\n",kase++,d[T]);

    }

    return ;

}