#include <bits/stdc++.h> using namespace std; queue<int>q; int dis[200005]; int main() { memset(dis,-1,sizeof(dis)); int n,k,ans=0; cin>>n>>k; dis[n]=0; q.push(n); while (q.size()>0){ int now=q.front(); q.pop(); if (nowk){ ans=dis[now]; cout<<ans; return 0; } if (now>0 && dis[now-1]-1){ dis[now-1]=dis[now]+1; q.push(now-1); } if (now<=100000 && dis[now+1]-1){ dis[now+1]=dis[now]+1; q.push(now+1); } if (now<=100000 && dis[now*2]-1){ dis[now2]=dis[now]+1; q.push(now2); } } return 0; }

广搜即可AC

代码：

略

#include <bits/stdc++.h>
using namespace std;
queue<int>q;
int dis[200005];
int main()
{
    memset(dis,-1,sizeof(dis));
    int n,k,ans=0;
    cin>>n>>k;
    dis[n]=0;
    q.push(n);
    while (q.size()>0){
        int now=q.front();
        q.pop();
        if (now==k){
            ans=dis[now];
            cout<<ans;
            return 0;
        }
        if (now>0 && dis[now-1]==-1){
            dis[now-1]=dis[now]+1;
            q.push(now-1);
        }
        if (now<=100000 && dis[now+1]==-1){
            dis[now+1]=dis[now]+1;
            q.push(now+1);
        }
        if (now<=100000 && dis[now*2]==-1){
            dis[now*2]=dis[now]+1;
            q.push(now*2);
        }
    }
    return 0;
}