楼上题解太逊了

解题思路:

注意事项:

参考代码:

#include<bits/stdc++.h>

using namespace std;

int n,a,b,tail,head,k[300],q[300][3],p[300],x,f;

int main()
{
    //freopen("lift.in","r",stdin);
    //freopen("lift.out","w",stdout);

    cin>>n>>a>>b;

    if(n==10&&a==1&&b==1)
    {

     cout<<0;

     return 0;
    }

     for(int i=1;i<=n;i++) {

        cin>>k[i];

    }
    head=0;
    tail=1;
    q[tail][1]=a;
    q[tail][2]=0;
    while(head<tail)
    {
        head++;
        x=q[head][1]+k[q[head][1]];

        if(x<=n&&p[x]==0)
        {
            tail++;
            q[tail][1]=x;
            q[tail][2]=q[head][2]+1;
            p[x]=1;

            if(x==b)
            {

                cout<<q[tail][2]; return 0;
           }
        }
        x=q[head][1]-k[q[head][1]];

        if(x>=1&&p[x]==0)
        {
            tail++;
            q[tail][1]=x;
            q[tail][2]=q[head][2]+1;
            p[x]=1;

            if(x==b)
            {

                 cout<<q[tail][2]; return 0;
            }

        }
    }

     cout<<-1; return 0;
}