HDU 2544 最短路(简单Dijkstra)

HDU 2544 最短路(简单Dijkstra)

http://acm.hdu.edu.cn/showproblem.php?pid=2544

题意:给你一个N个顶点的无向图,现在要你输出从1号点到N号点的最短距离.

分析:

直接Dijkstra模板,不谈了.

AC代码:

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;
const int maxn=100+10;
#define INF 1e9

struct Edge
{
    int from,to,dist;
    Edge(int f,int t,int d):from(f),to(t),dist(d){}
};

struct HeapNode
{
    int d,u;
    HeapNode(int d,int u):d(d),u(u){}
    bool operator <(const HeapNode &rhs)const
    {
        return d > rhs.d;
    }
};

struct Dijkstra
{
    int n,m;
    vector<Edge> edges;
    vector<int> G[maxn];
    bool done[maxn];
    int d[maxn];

    void init(int n)
    {
        this->n=n;
        for(int i=0;i<n;i++) G[i].clear();
        edges.clear();
    }

    void AddEdge(int from,int to,int dist)
    {
        edges.push_back(Edge(from,to,dist));
        m=edges.size();
        G[from].push_back(m-1);
    }

    void dijkstra()
    {
        priority_queue<HeapNode> Q;
        for(int i=0;i<n;i++) d[i]=INF;
        d[0]=0;
        memset(done,0,sizeof(done));
        Q.push(HeapNode(d[0],0));

        while(!Q.empty())
        {
            HeapNode x=Q.top(); Q.pop();
            int u=x.u;
            if(done[u]) continue;
            done[u]=true;

            for(int i=0;i<G[u].size();i++)
            {
                Edge &e=edges[G[u][i]];
                if(d[e.to] > d[u]+e.dist)
                {
                    d[e.to] = d[u]+e.dist;
                    Q.push(HeapNode(d[e.to],e.to));
                }
            }
        }
    }
}DJ;

int main()
{
    int n,m;
    while(scanf("%d%d",&n,&m)==2)
    {
        if(n==0 && m==0) break;
        DJ.init(n);

        while(m--)
        {
            int u,v,d;
            scanf("%d%d%d",&u,&v,&d);
            u--,v--;
            DJ.AddEdge(u,v,d);
            DJ.AddEdge(v,u,d);
        }
        DJ.dijkstra();
        printf("%d\n",DJ.d[n-1]);
    }
    return 0;
}