bfs

拯救大兵瑞恩 http://acm.hdu.edu.cn/showproblem.php?pid=4845

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<queue>
 4 #define mt(a,b) memset(a,b,sizeof(a))
 5 using namespace std;
 6 const int M=16;
 7 int mp[M][M][M][M];
 8 int key[M][M];
 9 bool vis[M][M][1<<11];
10 int n,m;
11 struct Q{
12     int x,y,step,mykey;
13 }now,pre;
14 queue<Q> q;
15 int dx[]={0,0,1,-1};
16 int dy[]={1,-1,0,0};
17 int bfs(){
18     now.x=1;
19     now.y=1;
20     now.step=0;
21     now.mykey=key[1][1];
22     mt(vis,0);
23     vis[1][1][now.mykey]=true;
24     while(!q.empty()) q.pop();
25     q.push(now);
26     while(!q.empty()){
27         pre=q.front();
28         q.pop();
29         if(pre.x==n&&pre.y==m) return pre.step;
30         for(int i=0;i<4;i++){
31             int tx=pre.x+dx[i];
32             int ty=pre.y+dy[i];
33             if(tx>=1&&tx<=n&&ty>=1&&ty<=m){
34                 int need=mp[pre.x][pre.y][tx][ty];
35                 if(need==-1||((pre.mykey>>need)&1)){
36                     now.x=tx;
37                     now.y=ty;
38                     now.step=pre.step+1;
39                     now.mykey=pre.mykey|key[tx][ty];
40                     if(!vis[tx][ty][now.mykey]){
41                         vis[tx][ty][now.mykey]=true;
42                         q.push(now);
43                     }
44                 }
45             }
46         }
47     }
48     return -1;
49 }
50 int main(){
51     int p,x1,y1,x2,y2,op;;
52     while(~scanf("%d%d%d",&n,&m,&p)){
53         scanf("%d",&p);
54         mt(mp,-1);
55         while(p--){
56             scanf("%d%d%d%d%d",&x1,&y1,&x2,&y2,&op);
57             mp[x1][y1][x2][y2]=op;
58             mp[x2][y2][x1][y1]=op;
59         }
60         scanf("%d",&p);
61         mt(key,0);
62         while(p--){
63             scanf("%d%d%d",&x1,&y1,&op);
64             key[x1][y1]|=(1<<op);
65         }
66         printf("%d\n",bfs());
67     }
68     return 0;
69 }

View Code

Catch That Cow http://poj.org/problem?id=3278

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<queue>
 4 #define mt(a,b) memset(a,b,sizeof(a))
 5 using namespace std;
 6 const int M=100010;
 7 int n,k;
 8 bool vis[M];
 9 struct G{
10     int val,step;
11 }now,pre;
12 queue<G> q;
13 void add(){
14     if(now.val>=0&&now.val<M){
15         if(!vis[now.val]){
16             vis[now.val]=true;
17             q.push(now);
18         }
19     }
20 }
21 int bfs(){
22     now.val=n;
23     now.step=0;
24     mt(vis,0);
25     vis[n]=true;
26     while(!q.empty()) q.pop();
27     q.push(now);
28     while(!q.empty()){
29         pre=q.front();
30         q.pop();
31         if(pre.val==k) return pre.step;
32         now.step=pre.step+1;
33         now.val=pre.val+1;
34         add();
35         now.val=pre.val-1;
36         add();
37         now.val=pre.val<<1;
38         add();
39     }
40 }
41 int main(){
42     while(~scanf("%d%d",&n,&k)){
43         printf("%d\n",bfs());
44     }
45     return 0;
46 }

View Code

迷宫问题 http://poj.org/problem?id=3984

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<queue>
 4 #define mt(a,b) memset(a,b,sizeof(a))
 5 using namespace std;
 6 const int M=8;
 7 int a[M][M],fa[M][M];
 8 bool vis[M][M];
 9 struct G{
10     int x,y;
11 }now,pre;
12 queue<G> q;
13 int dx[]={0,0,1,-1};
14 int dy[]={1,-1,0,0};
15 bool judge(int x){
16     if(x>=0&&x<5) return true;return false;
17 }
18 void bfs(){
19     mt(fa,-1);
20     mt(vis,0);
21     vis[0][0]=true;
22     now.x=0;
23     now.y=0;
24     while(!q.empty()) q.pop();
25     q.push(now);
26     while(!q.empty()){
27         pre=q.front();
28         q.pop();
29         if(pre.x==4&&pre.y==4) return ;
30         for(int i=0;i<4;i++){
31             int tx=pre.x+dx[i];
32             int ty=pre.y+dy[i];
33             if(judge(tx)&&judge(ty)&&!vis[tx][ty]&&!a[tx][ty]){
34                 vis[tx][ty]=true;
35                 fa[tx][ty]=i;
36                 now.x=tx;
37                 now.y=ty;
38                 q.push(now);
39             }
40         }
41     }
42 }
43 struct OUT{
44     int x,y;
45 }out[M*M];
46 int main(){
47     for(int i=0;i<5;i++){
48         for(int j=0;j<5;j++){
49             scanf("%d",&a[i][j]);
50         }
51     }
52     bfs();
53     int tx=4,ty=4,lo=0;
54     while(~fa[tx][ty]){
55         out[lo].x=tx;
56         out[lo].y=ty;
57         lo++;
58         int i=fa[tx][ty];
59         tx-=dx[i];
60         ty-=dy[i];
61     }
62     out[lo].x=0;
63     out[lo].y=0;
64     lo++;
65     for(int i=lo-1;i>=0;i--){
66         printf("(%d, %d)\n",out[i].x,out[i].y);
67     }
68     return 0;
69 }

View Code

Red and Black http://acm.hdu.edu.cn/showproblem.php?pid=1312

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<queue>
 4 #define mt(a,b) memset(a,b,sizeof(a))
 5 using namespace std;
 6 const int M=32;
 7 int n,m,sx,sy;
 8 char a[M][M];
 9 bool vis[M][M];
10 struct Q{
11     int x,y;
12 }now,pre;
13 queue<Q> q;
14 int dx[]={0,0,1,-1};
15 int dy[]={1,-1,0,0};
16 int bfs(){
17     mt(vis,0);
18     vis[sx][sy]=true;
19     now.x=sx;
20     now.y=sy;
21     while(!q.empty()) q.pop();
22     q.push(now);
23     while(!q.empty()){
24         pre=q.front();
25         q.pop();
26         for(int i=0;i<4;i++){
27             int tx=pre.x+dx[i];
28             int ty=pre.y+dy[i];
29             if(tx>=0&&tx<n&&ty>=0&&ty<m&&!vis[tx][ty]&&a[tx][ty]!='#'){
30                 vis[tx][ty]=true;
31                 now.x=tx;
32                 now.y=ty;
33                 q.push(now);
34             }
35         }
36     }
37     int res=0;
38     for(int i=0;i<n;i++){
39         for(int j=0;j<m;j++){
40             if(vis[i][j]) res++;
41         }
42     }
43     return res;
44 }
45 int main(){
46     while(~scanf("%d%d",&m,&n),m|n){
47         for(int i=0;i<n;i++){
48             scanf("%s",a[i]);
49             for(int j=0;j<m;j++){
50                 if(a[i][j]=='@'){
51                     sx=i;
52                     sy=j;
53                 }
54             }
55         }
56         printf("%d\n",bfs());
57     }
58     return 0;
59 }

View Code

Pet http://acm.hdu.edu.cn/showproblem.php?pid=4707

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<queue>
 4 #define mt(a,b) memset(a,b,sizeof(a))
 5 using namespace std;
 6 const int M=100010;
 7 struct G{
 8     struct E{
 9         int v,next;
10     }e[M<<1];
11     int le,head[M];
12     void init(){
13         le=0;
14         mt(head,-1);
15     }
16     void add(int u,int v){
17         e[le].v=v;
18         e[le].next=head[u];
19         head[u]=le++;
20     }
21 }g;
22 struct Q{
23     int id,step;
24 }now,pre;
25 queue<Q> q;
26 int D,n,t;
27 bool vis[M];
28 int bfs(){
29     int res=0;
30     mt(vis,0);
31     vis[0]=true;
32     now.id=0;
33     now.step=0;
34     while(!q.empty()) q.pop();
35     q.push(now);
36     while(!q.empty()){
37         pre=q.front();
38         q.pop();
39         if(pre.step<=D) res++;
40         if(pre.step==D) continue;
41         for(int i=g.head[pre.id];~i;i=g.e[i].next){
42             int v=g.e[i].v;
43             if(!vis[v]){
44                 vis[v]=true;
45                 now.id=v;
46                 now.step=pre.step+1;
47                 q.push(now);
48             }
49         }
50     }
51     return n-res;
52 }
53 int main(){
54     while(~scanf("%d",&t)){
55         while(t--){
56             scanf("%d%d",&n,&D);
57             g.init();
58             for(int i=0;i<n-1;i++){
59                 int u,v;
60                 scanf("%d%d",&u,&v);
61                 g.add(u,v);
62                 g.add(v,u);
63             }
64             printf("%d\n",bfs());
65         }
66     }
67     return 0;
68 }

View Code

end

posted on 2014-08-01 12:13 gaolzzxin 阅读(203) 评论(0) 收藏举报