题解

#include<iostream>
#include<queue>
using namespace std;
int n,k,a[200010];
queue<int>q;
int main(){
	cin>>n>>k;
	q.push(n);
	a[n]=0;
	while(q.size()!=0){
		int r=q.front();
		q.pop();
		if(r==k){
			cout<<a[k];
			break;
		}else{
			if(a[r-1]==0&&r>0){
				a[r-1]=a[r]+1;
				q.push(r-1);
			}
			if(a[r+1]==0&&(r+1)<=100000){
				a[r+1]=a[r]+1;
				q.push(r+1);
			}
			if(a[r*2]==0&&(r*2)<=100000){
				a[r*2]=a[r]+1;
				q.push(r*2);
			}
		}
	}
	return 0;
}