POJ 3278 Catch That Cow

BFS
 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <queue>
 5 using namespace std;
 6 int N,K;
 7 bool visited_flag[100002]={false};
 8 bool check(int x)
 9 {
10     if(0<=x&&x<=100000)
11         return true;
12     return false;
13 }
14 void bfs()
15 {
16     queue<int> Q;
17     Q.push(N);
18     Q.push(0);
19     visited_flag[N]=true;
20     int cur_pos;
21     int cur_deep;
22     while(!Q.empty()) {
23         cur_pos=Q.front();
24         Q.pop();
25         cur_deep=Q.front();
26         Q.pop();
27         if(cur_pos==K) {
28             printf("%d\n",cur_deep);
29             return ;
30         }
31         if(check(cur_pos-1)&&!visited_flag[cur_pos-1]) {
32             Q.push(cur_pos-1);
33             Q.push(cur_deep+1);
34             visited_flag[cur_pos-1]=true;
35         }
36         if(check(cur_pos+1)&&!visited_flag[cur_pos+1]) {
37             Q.push(cur_pos+1);
38             Q.push(cur_deep+1);
39             visited_flag[cur_pos+1]=true;
40         }
41         if(check(2*cur_pos)&&!visited_flag[cur_pos*2]) {
42             Q.push(cur_pos*2);
43             Q.push(cur_deep+1);
44             visited_flag[cur_pos*2]=true;
45         }
46     }
47 }
48 int main()
49 {
50     while(scanf("%d%d",&N,&K)!=EOF) {
51         memset(visited_flag,false,sizeof(visited_flag));
52         bfs();
53     }
54     return 0;
55 }