广搜之坐标移动

#include<iostream>
#include<queue>
using namespace std;
/*犯了粗心的错，注意审题*/
int n,b;
const int Kmax=5000+20;
bool vis[Kmax];
struct node{
    int x,step;
    node(int _x,int _step):
        x(_x),step(_step){}
};

int bfs(int a)
{
    queue<node> loca;
    loca.push({a,0});
    vis[a]=true;
    node t={a,0};
    while (!loca.empty()) {
       t=loca.front();
       loca.pop();
       if(t.x==b){
           return t.step;
       }
       if(t.x+1<=n&&(!vis[t.x+1])){
           vis[t.x+1]=true;
           loca.push({t.x+1,t.step+1});
       }
       if(t.x-1>=0&&(!vis[t.x-1])){
           vis[t.x-1]=true;
           loca.push({t.x-1,t.step+1});
       }
       if(t.x*2<=n&&(!vis[t.x*2])){
           vis[t.x*2]=true;
           loca.push({t.x*2,t.step+1});
       }
    }
    return 0;
}

int main()
{
    int a;
    cin>>n>>a>>b;
    cout<<bfs(a)<<endl;
    return 0;
}