题解

不准抄

#include <bits/stdc++.h>
using namespace std;

struct node{
    int x,t;
};
queue<node>que;
int n,k;
bool vis[100010];
int bfs(){
    while (!que.empty()){
        node a=que.front();
        que.pop();
        if (a.x==k) return a.t;
        if (a.x-1>=0 &&a.x-1<=100000 &&vis[a.x-1]==0){
            que.push({a.x-1,a.t+1});
            vis[a.x-1]=1;
        }
        if (a.x+1>=0 &&a.x+1<=100000 &&vis[a.x+1]==0){
            que.push({a.x+1,a.t+1});
            vis[a.x+1]=1;
        }
        if (a.x*2>=0 &&a.x*2<=100000 &&vis[a.x*2]==0){
            que.push({a.x*2,a.t+1});
            vis[a.x*2]=1;
        }
    }
}
int main(){
    cin>>n>>k;
    que.push({n,0});
    vis[n]=1;
    cout<<bfs();
    return 0;
}