#include<iostream>
#include<cstdio>
#include<queue>
#include<stdlib.h>
int sum=0;
int N,A,B;
typedef struct lift
{
int time,FLOOR;
bool operator < (const lift &a) const{
return time>a.time;
}
}floor;
int BFS(int k[],int k2[],int k1[]);
using namespace std;
int main()
{
while(scanf("%d",&N)!=EOF)
{
if(N==0){break;}
scanf("%d%d",&A,&B);
int k[201],k2[3]={0,1,-1},k1[202]={0};
int i;
for(i=1;i<=N;i++)
{
scanf("%d",&k[i]);
}
int t;
t=BFS(k,k2,k1);
printf("%d\n",t);
}
return 0;
}
int BFS(int k[],int k2[],int k1[])
{
priority_queue<floor> que;
floor start,next,cur;
start.FLOOR=A;
start.time=0;
k1[A]=1;
que.push(start);
while(!que.empty())
{
cur=que.top();
que.pop();
int z;
for(z=1;z<=2;z++)
{
next.FLOOR=cur.FLOOR+k[cur.FLOOR]*k2[z];
next.time=cur.time+1;
if((next.FLOOR>N)||(next.FLOOR<1)){continue;}
if(k1[next.FLOOR]==1){continue;}
k1[next.FLOOR]=1;//1代表已经走过;
if(next.FLOOR==B){return next.time;}
else{ que.push(next); }
}
}
return -1;
}
我觉得是循环那个地方超时了,但是没有想到怎么解决