C++ :

#include<stdio.h>
#include<string.h>

const int MAX = 500000 + 5;
const int INF = 0x3f3f3f3f;

int time[MAX];
int queue[MAX];
int bfs(int n,int k) {	
	memset(time,INF,sizeof(time));
	//queue<int> que;
	//que.push(n);
	int front,rear;
	front = rear = 0;
	rear++;
	queue[front] = n;
	time[n] = 0;
	
	while(front < rear) {
		//int t = que.front();que.pop();
		int t = queue[front];
		front++;
		if(t == k) break;
		if(t >= 1 && time[t - 1] == INF) {
			//que.push(t-1);
			queue[rear++] = t - 1;
			time[t-1] = time[t] + 1;
		}
		if(t <= k  &&  time[t * 2] == INF) {
			//que.push(t * 2);
			queue[rear++] = t * 2;
			time[t * 2] = time[t] + 1;
		}
		if(t <= k && time[t + 1] == INF) {
			queue[rear++] = t + 1;
			time[t + 1] = time[t] + 1;
		}
	}
	return time[k];
}
int main() {
	int n,k;
	while(~scanf("%d %d",&n,&k)) {
		int ans = bfs(n,k);
		printf("%d\n",ans);
	}
	return 0;
}

Java :

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;


public class Main {
	static int[][] d = {{1,-1},{1,1},{2,0}};
	static int[] step;
	static boolean[] vis;
	static final int MAX = 100005;
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while(in.hasNextInt()){
			int m = in.nextInt();
			int n = in.nextInt();
			vis = new boolean[MAX];
			step = new int[MAX];
			System.out.println(bfs(m,n));
		}
	}

	public static int bfs(int s, int e) {
		Queue q = new LinkedList();
		q.add(s);
		vis[s] = true;
		step[s] = 0;
		while (!q.isEmpty()) {
			int t = (int) q.poll();
			if (t == e)
				return step[t];
			for (int i = 0; i < 3; i++) {
				int xx = d[i][0] * t + d[i][1];
				if (xx >= MAX || xx < 0 || vis[xx])
					continue;
				vis[xx] = true;
				step[xx] = step[t] + 1;
				q.add(xx);
			}
		}
		return -1;
	}
}