POJ-2502(Dijikstra应用+最短路)

Subway

POJ-2502

• 这里除了直接相连的地铁站，其他图上所有的点都要连线，这里是走路的速度。
• 记住最后的结果需要四舍五入，否则出错。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<cmath>
#include<map>
using namespace std;
typedef pair<int,int> p;
const int INF=0x3f3f3f3f;
int sx,sy,ex,ey;
struct edge{
    int to;
    double cost;
    int next;
};
struct node{
    double dis;
    int to;
    node(){}
    node(int a,int b):dis(a),to(b){}
    bool operator<(const node& t)const{
        return dis>t.dis;
    }
};
edge ma[1500005];
int head[220];
int top;//指向头结点
double d[220];
int tn;//结点个数
int n=220;//最大结点数
map<pair<int,int>,int> mmap;
map<int,pair<int,int> >mmap1;
void addedge(int a,int b,double c){
    ma[top].to=b;
    ma[top].cost=c;
    ma[top].next=head[a];
    head[a]=top;
    top++;
}
void dijikstra(int s){
    priority_queue<node> que;
    for(int i=0;i<tn;i++){
        d[i]=INF;
    }
    d[s]=0;
    que.push(node(0,s));
    while(!que.empty()){
        node temp=que.top();
        que.pop();
        int v=temp.to;
        if(d[v]<temp.dis)
            continue;
        for(int h=head[v];h!=-1;h=ma[h].next){
            edge e=ma[h];
            if(d[e.to]>d[v]+e.cost){
                d[e.to]=d[v]+e.cost;
                que.push(node(d[e.to],e.to));
            }
        }
    }
}
bool isnode(int x,int y){
    if(!mmap.count(p(x,y))){
        mmap1[tn]=p(x,y);
        mmap[p(x,y)]=tn++;
        return true;
    }else return false;
}
double G[220][220];
int main(){
    memset(head,-1,sizeof(head));
    top=0;
    scanf("%d%d%d%d",&sx,&sy,&ex,&ey);
    mmap1[tn]=p(sx,sy);
    mmap[p(sx,sy)]=tn++;//0
    mmap1[tn]=p(ex,ey);
    mmap[p(ex,ey)]=tn++;//1
    int x,y;
    while(scanf("%d%d",&x,&y)!=EOF){
        int nx,ny;
        if(!mmap.count(p(x,y))){
            mmap1[tn]=p(x,y);
            mmap[p(x,y)]=tn++;
        }
        while(scanf("%d%d",&nx,&ny)!=EOF&&(nx!=-1||ny!=-1)){
            if(!mmap.count(p(nx,ny))){
                mmap1[tn]=p(nx,ny);
                mmap[p(nx,ny)]=tn++;
            }
            double distance=sqrt((nx-x)*(nx-x)+(ny-y)*(ny-y));
            distance/=40000.0;
            int ttn=mmap[p(nx,ny)];
            int ttnp=mmap[p(x,y)];
            addedge(ttn,ttnp,distance);
            addedge(ttnp,ttn,distance);
            G[ttn][ttnp]=distance;
            G[ttnp][ttn]=distance;
            x=nx,y=ny;
        }
    }
    for(int i=0;i<tn;i++){
        for(int j=0;j<tn;j++){
            if(G[i][j]==0&&i!=j){
                p p1=mmap1[i];
                sx=p1.first,sy=p1.second;
                p p2=mmap1[j];
                ex=p2.first,ey=p2.second;
                double distance1=sqrt((ex-sx)*(ex-sx)+(ey-sy)*(ey-sy));
                distance1/=10000.0;
                addedge(i,j,distance1);
                G[i][j]=distance1;
            }
        }
    }
    dijikstra(0);
    int final=d[1]*60.0+0.5;
    cout<<final<<endl;
    //system("pause");
    return 0;
}