问题标题: 酷町堂：5544：寻宝（find）

#include <iostream>
#include <cstring>
#include <queue> 
using namespace std;
int n, k;
bool flag[100005];
struct st{
    int t, x;
}cur;
queue<st>q;
int main(){
    cin>>n>>k;
    if(k<n){
        cout<<n-k<<endl;
        return 0;
    }
    q.push((st){0, n});
    while(1){
        cur=q.front();
        q.pop();
        flag[cur.x]=true;
        if(cur.x==k){
            cout<<cur.t<<endl;
            return 0;
        }
        if(cur.x*2<=100000&&!flag[cur.x*2]){
            q.push((st){cur.t+1,cur.x*2});  
        }
        if(cur.x+1<=100000&&!flag[cur.x+1]){
            q.push((st){cur.t+1,cur.x+1});  
        }
        if(cur.x-1>=0&&!flag[cur.x-1]){
            q.push((st){cur.t+1,cur.x-1});  
        }
    }
    return 0;
}