4月4日

Posted 2020-07-03 wolf940509

poj2627

题意:知道起点和终点，同时知道飞行速度和能在外面飞行的最长时间，问最小经过多少个洞可以到达终点

分析:裸的bfs

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <string>
 5 #include <vector>
 6 #include <algorithm>
 7 #include <set>
 8 #include <map>
 9 #include <bitset>
10 #include <cmath>
11 #include <queue>
12 #include <stack>
13 using namespace std;
14 const int maxn=2020;
15 typedef struct P
16 {
17     double x,y;
18     int rec;
19     bool vis;
20 }P;
21 P p[maxn];
22 double sx,sy,gx,gy;
23 double distance(double x1,double y1,double x2,double y2)
24 {
25     return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
26 }
27 double v,m;
28 int main()
29 {
30     cin>>v>>m;
31     cin>>sx>>sy>>gx>>gy;
32     int h=1;
33     while(cin>>p[h].x>>p[h].y)
34     {
35         p[h].rec=0;
36         p[h].vis=false;
37         h++;
38     }
39     double dist=v*m*60;
40     if(distance(sx,sy,gx,gy)<=dist)
41     {
42         cout<<"Yes, visiting 0 other holes."<<endl;
43         return 0;
44     }
45     P s;
46     queue<P> que;
47     s.x=sx,s.y=sy,s.rec=0,s.vis=true;
48     que.push(s);
49     int ans=0x3ffff;
50     int flag=0;
51     while(!que.empty())
52     {
53         P t=que.front();
54         que.pop();
55         if(distance(t.x,t.y,gx,gy)<=dist)
56         {
57             flag=1;
58             ans=min(ans,t.rec);
59         }
60         for(int i=1;i<h;i++)
61         {
62             if(distance(t.x,t.y,p[i].x,p[i].y)>dist||p[i].vis==true)
63                 continue;
64             p[i].rec=t.rec+1;
65             p[i].vis=true;
66             que.push(p[i]);
67         }
68     }
69     if(flag)
70         cout<<"Yes, visiting "<<ans<<" other holes."<<endl;
71     else
72         cout<<"No. "<<endl;
73     return 0;
74 }

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 poj2251

题意:在一个三维空间里面进行求最短路径

分析:与上面一题相同，bfs进行操作，注意这次扫的是六个方向

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <string>
  5 #include <vector>
  6 #include <algorithm>
  7 #include <set>
  8 #include <map>
  9 #include <bitset>
 10 #include <cmath>
 11 #include <queue>
 12 #include <stack>
 13 using namespace std;
 14 int l,r,c;
 15 const int maxn=50;
 16 typedef struct P
 17 {
 18     char c;
 19     int x,y;
 20     int id;
 21     int rec;
 22 }P;
 23 P s[maxn][maxn][maxn];
 24 int vis[maxn][maxn][maxn];
 25 int ans;
 26 int flag;
 27 int dx[]={-1,1,0,0,0,0},dy[]={0,0,-1,1,0,0},dz[]={0,0,0,0,1,-1};
 28 void bfs(int sx,int sy,int sz,int gx,int gy,int gz)
 29 {
 30     queue<P>p;
 31     if(sx==gx&&sy==gy&&sz==gy)
 32     {
 33         flag=1;
 34         ans=0;
 35     }
 36     else
 37     {
 38         p.push(s[sz][sx][sy]);
 39         vis[sz][sx][sy]=1;
 40         int nx=sx,ny=sy,nz=sz;
 41         while(!p.empty())
 42         {
 43             P t=p.front();
 44             p.pop();
 45             for(int i=0;i<6;i++)
 46             {
 47                 nx=t.x+dx[i];
 48                 ny=t.y+dy[i];
 49                 nz=t.id+dz[i];
 50                 if(ny<c&&ny>=0&&nx<r&&nx>=0&&nz>=1&&nz<=l&&!vis[nz][nx][ny])
 51                 {
 52                     vis[nz][nx][ny]=1;
 53                 if(s[nz][nx][ny].c==\'.\'){
 54                     s[nz][nx][ny].rec=t.rec+1;
 55                     p.push(s[nz][nx][ny]);
 56                 }
 57                  if(nx==gx&&ny==gy&&nz==gz)
 58                 {
 59                     flag=1;
 60                     ans=min(ans,(t.rec+1));
 61                 }
 62                 }
 63                 }
 64             }
 65         }
 66     }
 67 int main()
 68 {
 69     while(cin>>l>>r>>c)
 70     {
 71         if(l==0&&r==0&&c==0)  break;
 72         for(int i=1;i<=l;i++)
 73             for(int j=0;j<r;j++)
 74                 for(int k=0;k<c;k++)
 75                 {
 76                     cin>>s[i][j][k].c;
 77                     s[i][j][k].x=j;
 78                     s[i][j][k].y=k;
 79                     s[i][j][k].id=i;
 80                     s[i][j][k].rec=0;
 81                 }
 82         int sx,sy,sz,gx,gy,gz;
 83         for(int i=1;i<=l;i++)
 84             for(int j=0;j<r;j++)
 85                 for(int k=0;k<c;k++)
 86                 {
 87                     if(s[i][j][k].c==\'S\')
 88                     {
 89                         sx=j,sy=k,sz=i;
 90                     }else if(s[i][j][k].c==\'E\'){
 91                         gx=j,gy=k,gz=i;
 92                     }
 93                 }
 94         memset(vis,0,sizeof(vis));
 95         ans=0x3ffff;
 96         flag=0;
 97         bfs(sx,sy,sz,gx,gy,gz);
 98         if(flag)
 99         cout<<"Escaped in "<<ans<<" minute(s)."<<endl;
100         else
101         cout<<"Trapped!"<<endl;
102         }
103     return 0;
104 }

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