POJ 2502 Subway ( 最短路 && 最短路建图 )

#include<bits/stdc++.h>
#include<ext/pb_ds/priority_queue.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef pair< double, int > pii;
const int maxn = 200 + 10;
const double INF  = 1e30;
struct POINT{ int x, y; };
struct EDGE{ int v, nxt; double w; };

double v1, v2;
int Head[maxn], cnt, PointCnt;
double Dis[maxn];
EDGE Edge[maxn * maxn + maxn];
POINT Point[maxn];

inline void init()
{
    for(int i=0; i<=PointCnt; i++) Head[i] = -1;
    cnt = 0;
    PointCnt = 2;
}

double GetDis(int from, int to)
{
    double x1 = (double)Point[from].x, y1 = (double)Point[from].y;
    double x2 = (double)Point[to].x,   y2 = (double)Point[to].y;
    return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) );
}

inline void AddEdge(int from, int to, bool flag)
{
    double Weight;
    if(flag) Weight = GetDis(from, to) / v1;
    else Weight = GetDis(from, to) / v2;
    Edge[cnt].v = to;
    Edge[cnt].w = Weight;
    Edge[cnt].nxt = Head[from];
    Head[from] = cnt++;
}


double Dijkstra()
{
    for(int i=1; i<=PointCnt; i++) Dis[i] = INF;
    __gnu_pbds::priority_queue<pii,greater<pii>,pairing_heap_tag > Heap;
    Dis[1] = 0.0;
    Heap.push(make_pair(0.0, 1));
    while(!Heap.empty()){
        pii T = Heap.top(); Heap.pop();
        if(Dis[T.second] != T.first) continue;
        for(int i=Head[T.second]; i!=-1; i=Edge[i].nxt){
            int Eiv = Edge[i].v;
            if(Dis[Eiv] > Dis[T.second] + Edge[i].w){
                Dis[Eiv] = Dis[T.second] + Edge[i].w;
                Heap.push(make_pair(Dis[Eiv], Eiv));
            }
        }
    }
    return Dis[2];
}

int main(void)
{
    v1 = 40000.0/60.0;
    v2 = 10000.0/60.0;
    PointCnt = maxn - 1;
    while(~scanf("%d %d", &Point[1].x, &Point[1].y)){
        scanf("%d %d", &Point[2].x, &Point[2].y);
        init();
        int x, y;
        while(scanf("%d %d", &x, &y)!=EOF){
            PointCnt++;
            Point[PointCnt].x = x;
            Point[PointCnt].y = y;
            int pre = PointCnt;
            while(~scanf("%d %d", &x, &y) && !(x==-1 && y==-1)){
                PointCnt++; int now = PointCnt;
                Point[PointCnt].x = x;
                Point[PointCnt].y = y;
                AddEdge(pre, now, true);
                AddEdge(now, pre, true);
                pre = now;
            }
        }

        for(int i=1; i<=PointCnt; i++){
            for(int j=i; j<=PointCnt; j++){
                if(j != i){
                    AddEdge(i, j, false);
                    AddEdge(j, i, false);
                }
            }
        }

        printf("%.0lf\n", Dijkstra());
    }
    return 0;
}