64分求调(必回关)

#include <bits/stdc++.h>
using namespace std;
const int N = 1001;
int arr[N], n, a, b , k;
bool vis[N];
int ans = INT_MAX;
void dfs(int a, int times) {
    if (times >= ans) {
        return;
    }
    if (a == b) {
        ans = times;
        return;
    }
    vis[a] = 1;
    int up = a + arr[a];
    if(vis[up] == 0 && up <= n)
    {
        dfs(up , times + 1);
    }
    int down = a - arr[a];
    if(vis[down] == 0 && down >= 0)
    {
        dfs(down , times + 1);
    }
}
int main() {
    cin >> n >> a >> b;
    for (int i = 1; i <= n; i++) {
        cin >> arr[i];
    }
    dfs(a, 0);
    if(ans == INT_MAX)cout << -1;
    else cout << ans;
    return 0;
}