UVA 11374 Airport Express

虽然这个题写的很挫。但还是水一下。

#include <iostream>
#include <vector>
#include <queue>
#include <cstring>
#include <cstdio>
#define INF 1 << 20
using namespace std;
typedef pair<int,int> pii;
int N,S,E,M,K;
int G[505][505],f[505],g[505],T[1010][3];
int path1[1000];//从起点s到a的逆序路径
int path2[1000];//从b到终点e的顺序路径

void Read_Graph()
{
    memset(path1,0,sizeof(path1));
    memset(path2,0,sizeof(path2));
    for(int i = 0;i <= N;i++)
        for(int j = 0;j <= N;j++)
            G[i][j] = INF;
    int i,s,e,l;
    scanf("%d",&M);
    for(i = 1;i <= M;i++)
    {
        scanf("%d%d%d",&s,&e,&l);
        G[s][e] = G[e][s] = l;
    }
    scanf("%d",&K);
    for(i = 1;i <= K;i++)
        scanf("%d%d%d",&T[i][0],&T[i][1],&T[i][2]);
}

void Dijkstra(int start,int d[])
{
    priority_queue< pii,vector<pii>,greater<pii> > q;

    int ith,i;

    for(i = 1;i <= N;i++)   d[i] = INF;
    d[start] = 0;
    q.push(make_pair(0,start));

    while(!q.empty())
    {
        while(!q.empty() && q.top().first > d[q.top().second])
        {
            q.pop();
        }
        if(q.empty())   break;
        ith = q.top().second;
        q.pop();
        for(i = 1;i <= N;i++)
        {
            if(d[i] > d[ith] + G[ith][i])
            {
                d[i] = d[ith] + G[ith][i];
                q.push(make_pair(d[i],i));
            }
        }
    }
}

void solve()
{
    int i,a,b,t,temp1,temp2,dis,pos,count1,count2;
    Dijkstra(S,f);
    Dijkstra(E,g);
    int ans = f[E];
    a = 0;
    //查询每一条商业线
    for(i = 1;i <= K;i++)
    {
        temp1 = T[i][0];
        temp2 = T[i][1];
        t = T[i][2];

        if(f[temp1] + t + g[temp2] < ans)
        {
            ans = f[temp1] + t + g[temp2];
            a = temp1;
            b = temp2;
        }

        if(f[temp2] + t + g[temp1] < ans)
        {
            ans = f[temp2] + t + g[temp1];
            a = temp2;
            b = temp1;
        }
    }

    if(a)//如果用掉了商业线的票
    {
        dis = f[a];
        pos = a;
        count1 = 0;
        path1[count1] = pos;
        while(dis != 0)
        {
            for(i = 1;i <= N;i++)
            {
                if(f[i] + G[i][pos] == f[pos])
                {
                    pos = i;
                    dis = f[i];
                    path1[++count1] = pos;
                    break;
                }
            }
        }

        dis = g[b];
        pos = b;
        count2 = 0;
        path2[count2] = pos;
        while(dis != 0)
        {
            for(i = 1;i <= N;i++)
            {
                if(g[i] + G[i][pos] == g[pos])
                {
                    pos = i;
                    dis = g[i];
                    path2[++count2] = pos;
                    break;
                }
            }
        }
        printf("%d",path1[count1]);
        for(i = count1 - 1;i >= 0;i--)
            printf(" %d",path1[i]);
        for(i = 0;i <= count2;i++)
            printf(" %d",path2[i]);
        printf("\n");
        printf("%d\n",a);
    }

    else
    {
        dis = f[E];
        pos = E;
        count1 = 0;
        path1[count1] = pos;
        while(dis != 0)
        {
            for(i = 1;i <= N;i++)
            {
                if(f[i] + G[i][pos] == f[pos])
                {
                    pos = i;
                    dis = f[i];
                    path1[++count1] = pos;
                    break;
                }
            }
        }
        printf("%d",path1[count1]);
        for(i = count1 - 1;i >= 0;i--)
            printf(" %d",path1[i]);
        printf("\n");
        printf("Ticket Not Used\n");
    }
    printf("%d\n",ans);

}
int main()
{
    bool first = true;
    while(scanf("%d%d%d",&N,&S,&E) == 3)
    {
        if(first)   first = false;
        else    printf("\n");
        Read_Graph();
        solve();
    }
    return 0;
}