BZOJ 1646: [Usaco2007 Open]Catch That Cow 抓住那只牛 (BFS)

2016年4月10日 0 作者 CrazyKK

1646: [Usaco2007 Open]Catch That Cow 抓住那只牛

Time Limit: 5 Sec  Memory Limit: 64 MB
Submit: 915  Solved: 441


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?



* Line 1: Two space-separated integers: N and K



* Line 1: The least amount of time, in minutes, it takes for Farmer John to catch the fugitive cow.


Sample Input

5 17
Farmer John starts at point 5 and the fugitive cow is at point 17.

Sample Output



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.