POJ-3278-Catch That Cow(bfs)
Farmer John has been informed of the location of a fugitive cow and wants to catch her immediately. He starts at a point N (0 ≤ N ≤ 100,000) on a number line and the cow is at a point K (0 ≤ K ≤ 100,000) on the same number line. Farmer John has two modes of transportation: walking and teleporting.
- Walking: FJ can move from any point X to the points X",“1 or X + 1 in a single minute
- Teleporting: FJ can move from any point X to the point 2 × X in a single minute.
If the cow, unaware of its pursuit, does not move at all, how long does it take for Farmer John to retrieve it?
Input
Line 1: Two space-separated integers: N and K
Output
Line 1: The least amount of time, in minutes, it takes for Farmer John to catch the fugitive cow.
Sample Input
5 17
Sample Output
4
Hint
The fastest way for Farmer John to reach the fugitive cow is to move along the following path: 5-10-9-18-17, which takes 4 minutes.
题意:
农场主的牛不见了,主人和牛在一条直线上,且牛没有新的目标,它不会走动,主人的位置是你 n,牛的位置是 k,主人可以有三种走路的方法,右左(距离+-1),闪现(距离+x,x 为当前位置),每走一步,一分钟,问几分钟主人能找到牛。bfs 搜索方向即为三个“方向”。搜索所有走法;
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