#642. 1646. [Usaco2007 Open]Catch That Cow 抓住那只牛

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

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

题目描述

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?

农夫约翰被通知,他的一只奶牛逃逸了!所以他决定,马上幽发,尽快把那只奶牛抓回来.

他们都站在数轴上.约翰在N(O≤N≤100000)处,奶牛在K(O≤K≤100000)处.约翰有

两种办法移动,步行和瞬移:步行每秒种可以让约翰从z处走到x+l或x- l处;而瞬移则可让他在1秒内从x处消失,在2x处出现.然而那只逃逸的奶牛,悲剧地没有发现自己的处境多么糟糕,正站在那儿一动不动.

那么,约翰需要多少时间抓住那只牛呢?

输入格式

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

    仅有两个整数N和K.

输出格式

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

    最短的时间.

样例

样例输入

5 17  

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

样例输出

4  

  

OUTPUT DETAILS:  

  

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.

数据范围与提示