典型广搜

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

int a[205],vis[205];

struct node{
    int p,step;
};

int main(){
    int n,x,y;
    cin >> n >> x >> y;
    for(int i = 0;i < n;i ++) cin >> a[i];
    queue<node> q;
    q.push({x - 1,0});
    vis[x - 1] = 1;
    while(!q.empty()){
        int ip = q.front().p,istep = q.front().step;
        q.pop();
        if(ip == y - 1){
            cout << istep;
            return 0;
        }
        if(ip - a[ip] >= 0 and vis[ip - a[ip]] == 0){
            vis[ip - a[ip]] = 1;
            q.push({ip - a[ip],istep + 1});
        }
        if(ip + a[ip] <= n - 1 and vis[ip + a[ip]] == 0){
            vis[ip + a[ip]] = 1;
            q.push({ip + a[ip],istep + 1});
        }
    }
    cout << -1;
    return 0;
}