So easy（？）

这里用了BFS算法，题解如下：

#include<iostream>
#include<queue>
#include<cstring>
using namespace std;
const int MAX=100000;
int N,K;
int vis[MAX+5];
struct node{
    int pos;
    int time;
};
void BFS(){
    queue<node> q;
    q.push({N,0});
    vis[N]=0;
    while(q.size()){
        node now=q.front();
        q.pop();
        if(now.pos==K){
            cout<<now.time;
            return;
        }
        int next_pos[3]={now.pos-1,now.pos+1,now.pos*2};//步数有三种情况
        for(int i=0;i<3;i++){
            int np=next_pos[i];
           //边界情况
            if(np<0||np>MAX){
                continue;
            }
            if(vis[np]==-1){
                vis[np]=now.time+1;
                q.push({np,now.time+1});
            }
        }
    }
}
signed main(){
    cin>>N>>K;
    memset(vis,-1,sizeof(vis));//初始化vis数组，都为-1
    BFS();
}