开开心心的写了，我在其他机构里做过这一题

#include <bits/stdc++.h>
using namespace std;

struct stu
{
    long long x,number = 0;
}q[43000],s,u,v;
long long n,a1,b,a[205] = {},rear = 0,front = 1;
bool vis[205] = {},flag = false;

int main()
{
    cin >> n >> a1 >> b;
    if(a1 == b)
    {
        cout << 0;
        return 0;
    }
    for(int i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    s.x = a1;
    s.number = 0;
    q[++rear] = s;
    vis[s.x] = true;
    while(front <= rear)
    {
        u = q[front++];
        for(int i = 1; i <= 2; i++)
        {
            if(i == 1)
            {
                v.x = u.x + a[u.x];
            }
            else
            {
                v.x = u.x - a[u.x];
            }
            v.number = u.number + 1;
            if(v.x <= 0 || v.x > n)
            {
                continue;
            }
            if(vis[v.x] == true)
            {
                continue;
            }
            if(v.x == b)
            {
                cout << v.number;
                flag = true;
                return 0;
            }
            q[++rear] = v;
            vis[v.x] = true;
        }
    }
    if(flag == false)
    {
        cout << -1;
    }
    return 0;
}