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🐖🌊✨❎→张老帅

2026-07-23 15:22:31

发布于：广东

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#include<bits/stdc++.h>
using namespace std;
const int MAXN=100010;
int n,k;
int vis[MAXN];
void bfs(){
    memset(vis,-1,sizeof(vis));
    queue<int> q;
    q.push(n);
    vis[n]=0;
    while(!q.empty()){
        int u=q.front();q.pop();
        if(u==k){
            cout<<vis[u]<<endl;
            return;
        }
        if(u-1>=0&&vis[u-1]==-1){
            vis[u-1]=vis[u]+1;
            q.push(u-1);
        }
        if(u+1<MAXN&&vis[u+1]==-1){
            vis[u+1]=vis[u]+1;
            q.push(u+1);
        }
        if(u<k&&vis[2*u]==-1){
            vis[2*u]=vis[u]+1;
            q.push(2*u);
        }
    }
}
int main(){
    cin>>n>>k;
    if(n>=k) cout<<n-k<<endl;
    else bfs();
    return 0;
}