[kuangbin带你飞]专题一 简单搜索 C - Catch That Cow poj 3278

C - Catch That Cow

Time Limit:2000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

Submit Status

Description

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：给你N和K  求N -> K 要几分钟  

有以下变化

N -> 2*N   1分钟

N -> N+1 1分钟

N ->N-1 1分钟

用BFS 当 N>=K  输出N-K

N<K  用BFS搜