题解

一定程度上借鉴了AC君的代码

#include<bits/stdc++.h>
using namespace std;
const int maxn=2e2+9;
int d[maxn],k[maxn];
int main(){
	int n,a,b;
	cin>>n>>a>>b;
	queue<int> que;
	for(int i=1;i<=n;i++){
		cin>>k[i];
	}
    memset(d,-1,sizeof(d));
    d[a]=0;
    que.push(a);
    while(que.size()){
        int r=que.front();
        que.pop();
		if(r+k[r]<=n&&d[r+k[r]]==-1){
            d[r+k[r]]=d[r]+1;
            que.push(r+k[r]);
        }
        if(r-k[r]>=1&&d[r-k[r]]==-1){
            d[r-k[r]]=d[r]+1;
            que.push(r-k[r]);
        }
    }
    cout<<d[b];
	return 0;
}