Catch That Cow

M - Catch That Cow

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.

#include<iostream>#include<cstring>#include<algorithm>#include<stdio.h>#include<queue>typedef long long ll;#define maxn 100010using namespace std;#define cle(n)    memset(n,0,sizeof(n))int n,k;int vis[2*maxn];struct Node{    int x,step;    Node(){}    Node(int x,int step):x(x),step(step){}};int bfs(){    queue<Node>que;    que.push(Node(n,0));    vis[n]=1;    while(que.size())    {        Node node=que.front();         que.pop();        for(int i=0;i<3;i++)        {            int nx=0;            if(i==0)                 nx=node.x-1;            if(i==1)                nx=node.x+1;            if(i==2)                nx=node.x*2;            if(nx==k)            {               cout<<node.step+1<<endl; return 0;            }            if(nx<0||nx>100000)                continue;            if(!vis[nx])            {                vis[nx]=1;                que.push(Node(nx,node.step+1));            }        }    }}int main(){    while(~scanf("%d%d",&n,&k))    {     cle(vis);   if(n<k)      bfs();      if(n==k)        cout<<0<<endl;      if(n>k)        cout<<n-k<<endl;    }    return 0;}