题解BFS

#include <bits/stdc++.h>
using namespace std;
int a[205];
int d[205];
int n,m,k;
int main(){

cin>>k>>n>>m;
for(int i=1;i<=k;i++){
	cin>>a[i];
	d[i]=-1;
}
d[n]=0;
queue <int> que;
que.push(n);
bool op=1;
while(que.size()){
	int r=que.front();
	que.pop();
	if(r==m){
		op=0;
		cout<<d[r];
		break;
	}
	if(r>=a[r]+1&&d[r-a[r]]==-1){
		d[r-a[r]]=d[r]+1;
		que.push(r-a[r]);
	}
	if(r<=200-a[r]&&d[r+a[r]]==-1){
		d[r+a[r]]=d[r]+1;
		que.push(r+a[r]);
	}
}
if(op){
	cout<<-1;
}
return 0;

}