POJ 3287 (基础BFS) Catch That Cow

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <queue>
 5 using namespace std;
 6 int n, k;
 7 const int maxn = 100000;
 8 int visited[maxn + 10];    //判重标记
 9 struct Step
10 {
11     int x;
12     int steps;
13     Step(int xx, int s):x(xx), steps(s){}
14 };
15 queue<Step> q;
16 int main(void)
17 {
18     scanf("%d%d", &n, &k);
19     memset(visited, 0, sizeof(visited));
20     q.push(Step(n, 0));
21     visited[n] = 1;
22     while(!q.empty())
23     {
24         Step s = q.front();
25         if(s.x == k)
26         {//找到目标
27             printf("%d\n", s.steps);
28             return 0;
29         }
30         else
31         {
32             if(s.x - 1 >= 0 && !visited[s.x-1])
33             {
34                 q.push(Step(s.x-1, s.steps+1));
35                 visited[s.x-1] = 1;
36             }
37             if(s.x + 1 <= maxn && !visited[s.x+1])
38             {
39                 q.push(Step(s.x+1, s.steps+1));
40                 visited[s.x+1] = 1;
41             }
42             if(s.x*2 <= maxn && !visited[s.x*2])
43             {
44                 q.push(Step(s.x*2, s.steps+1));
45                 visited[s.x*2] = 1;
46             }
47             q.pop();
48         }
49     }
50     return 0;
51 }