hdu 1245 Saving James Bond 策画几何+最短路 最短路求步数最少的路径

#include<stdio.h>
#include<string.h>
#include<math.h>
#define inf 0x3fffffff
#define N 200
#define eps  1e-10
#include<queue>
using namespace std;
struct node {
 int x,y;
}ma[N];
struct nodee {
int u,v,next;
double w;
}bian[N*N];
int yong,head[N],n;
void addedge(int u,int v,double w) {
bian[yong].u=u;
bian[yong].v=v;
bian[yong].w=w;
bian[yong].next=head[u];
head[u]=yong++;
}
double MIN(double  a,double b) {
return a>b?b:a;
}
void  bfs() {//宽搜
    queue<int>q;
    double dist[N];
    int step[N],i,visit[N];
    memset(visit,0,sizeof(visit));
    while(!q.empty())
        q.pop();
    q.push(0);
    for(i=1;i<=n+1;i++)
        dist[i]=inf;
    step[0]=0;
   dist[0]=0;visit[0]=1;
    while(!q.empty()){
        int cur=q.front();
        q.pop();
        for(i=head[cur];i!=-1;i=bian[i].next) {
            int v=bian[i].v;
            if((dist[v]>dist[cur]+bian[i].w+eps||fabs(dist[v]-dist[cur]-bian[i].w)<=eps)&&step[v]>step[cur]+1&&visit[v]==0) {//判断条件如果相等就要比较它的最少的步数
                step[v]=step[cur]+1;
                dist[v]=dist[cur]+bian[i].w;
                visit[v]=1;
                q.push(v);
            }
        }
    }
    if(dist[n+1]<inf)
        printf("%.2f %d\n",dist[n+1],step[n+1]);
    else
        printf("can't be saved\n");
        return ;
}
int main() {
     int i,j,s,t;
     double limit,minn;
     while(scanf("%d%lf",&n,&limit)!=EOF) {
            t=n+1;s=0;
            yong=0;
            memset(head,-1,sizeof(head));
        for(i=1;i<=n;i++) {
            scanf("%d%d",&ma[i].x,&ma[i].y);
          minn=MIN(fabs(50.0-fabs(1.0*ma[i].x)),fabs(50.0-fabs(1.0*ma[i].y)));
            if(minn<limit+eps) {//将符合条件的边
                addedge(i,t,minn);
                addedge(t,i,0);//
            }
            minn=fabs(sqrt(1.0*ma[i].x*ma[i].x+1.0*ma[i].y*ma[i].y)-7.5);
             if(minn<limit+eps) {
              addedge(s,i,minn);//
              addedge(i,s,0);//
             }
     }
    if(limit+eps>42.50) {//如果可以直接跳到岸上就直接输出
                printf("42.50 1\n");
                continue;
            }
      for(i=1;i<n;i++)
      for(j=i+1;j<=n;j++) {
        minn=inf;
        minn=MIN(minn,sqrt(1.0*(ma[i].x-ma[j].x)*(ma[i].x-ma[j].x)+1.0*(ma[i].y-ma[j].y)*(ma[i].y-ma[j].y)));
        if(minn<limit+eps) {
            addedge(i,j,minn);
            addedge(j,i,minn);//双向边
        }
      }
      bfs();
     }
return 0;
}