poj 3278

#include <queue>
#include <cstring>
using namespace std;
const int maxn = 100005;
bool vis[maxn];
int dir[2] = {1, -1};
int n, k;
struct 
{
	int x, step;
};
bool check(node m)
{
	if(m.x < 0 || m.x > 100000 || vis[m.x])
		return false;
	return true;
}
int bfs(node start)
{
	queue <node> q;
	q.push(start);
	node cur;
	node next;
	while(q.size())
	{
		cur = q.front();
		q.pop();
		for(int i = 0; i < 2; i++)
		{
			next.x = cur.x + dir[i];
			next.step = cur.step + 1;
			if(check(next))
			{
				q.push(next);
				vis[next.x] = true;
				if(next.x == k)
					return next.step;
			}
		}
		next.x = cur.x * 2;
		next.step = cur.step + 1;
		if(check(next))
		{
			q.push(next);
			vis[next.x] = true;
			if(next.x == k)
				return next.step;
		}
	}
	return -1;
}
int main()
{
	while(cin >> n >> k)
	{
		memset(vis, false, sizeof vis);
		node m;
		m.x = n;
		m.step = 0;
		if(n >= k)
			cout << n - k << endl;
		else
			cout << bfs(m) << endl;
	}
	return 0;
}