五颜六色 https://www.luogu.com.cn/record/149116586

#include<bits/stdc++.h>
using namespace std;
int n,k[201],ar,op,mins=-1u>>1;
bool getr[201];
void dfs(int dep,int step=0){
	if(getr[dep])return;
	if(dep<1||dep>n)return;
	if(dep==op){
		mins=min(mins,step);
		return;
	}
	getr[dep]=1;
	dfs(dep+k[dep],step+1);
	dfs(dep-k[dep],step+1);
	getr[dep]=0;
}
signed main(){
	cin>>n>>ar>>op;
	for(int i=1;i<=n;i++)
		cin>>k[i];
	dfs(ar);
	cout<<mins;
	return 0;
}