文件目录

#include <bits/stdc++.h>
using namespace std;
int n, a, b, k[250];
struct P
{
    int lc;
    int step;
    P(int x, int s)
    {
        lc = x;
        step = s;
    }
};
queue<P> q;
int vis[250];
int bfs(int x)
{
    q.push(P(x, 0));
    vis[x] = 1;
    while (!q.empty())
    {
        P u = q.front();
        q.pop();
        if (u.lc == b)
            return u.step;
        if (u.lc + k[u.lc] <= n && vis[u.lc + k[u.lc]] == 0)
        {
            q.push(P(u.lc + k[u.lc], u.step + 1));
            vis[u.lc + k[u.lc]] = 1;
        }
        if (u.lc - k[u.lc] >= 1 && vis[u.lc - k[u.lc]] == 0)
        {
            q.push(P(u.lc - k[u.lc], u.step + 1));
            vis[u.lc - k[u.lc]] = 1;
        }
    }
    return -1;
}
int main()
{
    cin >> n >> a >> b;
    for (int i = 1; i <= n; i++)
        cin >> k[i];
    cout << bfs(a);
    return 0;
}