hdu2066 最短路 dijkstra

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建立超级源点和超级汇点，家是超级源点s=0，超级汇点t=所有城市最大值+1，超级源点s到相连的城市的边权=想去的城市到超级汇点t的边权=0。只需要求出超级源点到超级汇点的最短路即可。用邻接矩阵的dijkstar1()耗时57ms，用了优先队列+邻接表的dijkstra2()耗时0ms，优化还是很明显的。

#include<iostream>#include<cstring>#include<cstdlib>#include<cstdio>#include<cmath>#include<string>#include<map>#include<set>#include<algorithm>#include<vector>#include<queue>#include<stack>#include<sstream>#define LL long long#define OJ_DEBUG 0#define READ_FILE 1using namespace std;const int NN_MAX = 1010;const int MM_MAX = NN_MAX*NN_MAX;const int INF = 0x3f3f3f3f;struct Edge{    int from,to,dis;    Edge(int a1=0,int a2=0,int a3=0):from(a1),to(a2),dis(a3){};    bool operator < (const Edge& ohe) const {return dis > ohe.dis;}};/**********************************************************/int n,m,s,t,lenEdge;int d[NN_MAX],paths[NN_MAX][NN_MAX];bool vis[NN_MAX];vector<Edge>theEdge;vector<int>G[NN_MAX];/**********************************************************/int min_2 (int x,int y) {return x<y?x:y;}int max_2 (int x,int y) {return x>y?x:y;}void dijkstra1();void dijkstra2();/**********************************************************/int main(){    if (READ_FILE) freopen ("in.txt","r",stdin);    int tt,ss,dd;    while(scanf("%d %d %d",&tt,&ss,&dd)!=EOF)    {        //memset(paths,0x3f,sizeof(paths));        //for(int i=0;i<NN_MAX;i++) paths[i][i]=0;        theEdge.clear(); lenEdge=0;        for(int i=0;i<NN_MAX;i++) G[i].clear();        t=0,s=0;        int a1,a2,a3;        for(int i=0;i<tt;i++){            scanf("%d %d %d",&a1,&a2,&a3);            t=(t<a1?a1:t); t=(t<a2?a2:t);            //if(paths[a1][a2]>a3)                //paths[a1][a2]=paths[a2][a1]=a3;            theEdge.push_back(Edge(a1,a2,a3)); G[a1].push_back(lenEdge++);            theEdge.push_back(Edge(a2,a1,a3)); G[a2].push_back(lenEdge++);        }        ++t;        for(int i=0;i<ss;i++){            scanf("%d",&a1);            //paths[0][a1]=0;            theEdge.push_back(Edge(0,a1,0)); G[0].push_back(lenEdge++);        }        for(int i=0;i<dd;i++){            scanf("%d",&a1);            //paths[a1][t]=0;            theEdge.push_back(Edge(a1,t,0)); G[a1].push_back(lenEdge++);        }        //dijkstra1();        dijkstra2();        printf("%d\n",d[t]);    }    return 0;}void dijkstra1(){    for(int i=0;i<=t;i++) d[i]=(i==s?0:INF);    memset(vis,0,sizeof(vis));    for(int i=0;i<=t;i++){        int x,mm=INF;        for(int i=0;i<=t;i++)            if(!vis[i] && d[i]<mm)                mm=d[x=i];        vis[x]=1;        for(int i=0;i<=t;i++){            if(!vis[i] && d[i]>d[x]+paths[x][i])                d[i]=d[x]+paths[x][i];        }    }}struct HeapNode {    int u,d;    HeapNode(int a1=0, int a2=0):u(a1),d(a2){};    bool operator < (const HeapNode& rhs) const {return d>rhs.d;}};void dijkstra2(){    for(int i=0;i<=t;i++) d[i]=(i==s?0:INF);    memset(vis,0,sizeof(vis));    priority_queue<HeapNode> pq;    pq.push(HeapNode(s,0));    while(!pq.empty())    {        HeapNode x = pq.top(); pq.pop();        if(vis[x.u]) continue;        vis[x.u]=1;        for(int i=0;i<G[x.u].size();i++){            Edge& e = theEdge[G[x.u][i]];            if(!vis[e.to] && d[e.to]>d[x.u]+e.dis){                d[e.to]=d[x.u]+e.dis;                pq.push(HeapNode(e.to,d[e.to]));            }        }    }}

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