HDU ACM 2066 一个人的旅行 (SPFA)

http://acm.hdu.edu.cn/showproblem.php?pid=2066

 

用来练习SPFA

有多个出发点事不必做多次的SPFA,只要把多个顶点初始化为0即.

 

#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
const int MAX = 1100;
const int INF = 0x3fffffff;
int map[MAX][MAX];
int start[MAX];
int End[MAX];
int dis[MAX];
int used[MAX];
int mark;
int T,S,D;
int SPFA()
{
    int i;
    for(i=0;i<mark+1;i++)
    {
        dis[i] = INF;
    }
    queue <int> q;
    for(i=0;i<S;i++)
    {
        dis[start[i]] = 0;
        q.push(start[i]);
        used[start[i]] = 1;
    }
    while(!q.empty())
    {
        int mid;
        mid = q.front();
        q.pop();
        used[mid] = 0;
        for(i=0;i<mark+1;i++)
        {
            if(dis[i] > dis[mid] + map[mid][i])
            {
                dis[i] = dis[mid] + map[mid][i];
                if(!used[i])
                {
                    q.push(i);
                    used[i] = 1;
                }
            }
        }
    }
    int MIN = INF;
    for(i=0;i<D;i++)
    {
        MIN = min(MIN,dis[End[i]]);
    }
    return MIN;
}
int main()
{
    while(cin>>T>>S>>D)
    {
        int i,j;
        for(i=0;i<MAX;i++)
        {
            for(j=0;j<MAX;j++)
            {
                map[i][j] = INF;
            }
        }
        mark = 0;
        for(i=0;i<T;i++)
        {
            int a,b,c;
            cin>>a>>b>>c;
            if(c < map[a][b])
            {
                map[a][b] = map[b][a] = c;
            }
            mark = max(mark,a);
            mark = max(mark,b);
        }
        for(i=0;i<S;i++)
        {
            cin>>start[i];
        }
        for(i=0;i<D;i++)
        {
            cin>>End[i];
        }
        cout<<SPFA()<<endl;
    }
    return 0;
}