HDU 1548.A strange lift

 1 /*
 2 By:OhYee
 3 Github:OhYee
 4 Email:oyohyee@oyohyee.com
 5 Blog:http://www.cnblogs.com/ohyee/
 6 
 7 かしこいかわいい？
 8 エリーチカ！
 9 要写出来Хорошо的代码哦~
10 */
11 
12 #include <cstdio>
13 #include <algorithm>
14 #include <cstring>
15 #include <cmath>
16 #include <string>
17 #include <iostream>
18 #include <vector>
19 #include <list>
20 #include <queue>
21 #include <stack>
22 using namespace std;
23 
24 //DEBUG MODE
25 #define debug 0
26 
27 //循环
28 #define REP(n) for(int o=0;o<n;o++)
29 
30 const int maxn = 205;
31 int k[maxn];
32 int N;
33 
34 int BFS(int s,int v) {
35     if(s == v)
36         return 0;
37 
38     queue<int> Q;
39     bool visited[maxn];
40     memset(visited,false,sizeof(visited));
41     int dis[maxn];
42     memset(dis,0,sizeof(dis));
43 
44     Q.push(s);
45     visited[s] = true;
46     while(!Q.empty()) {
47         int th = Q.front();
48         Q.pop();
49 
50         //达到终点
51         if(th == v)
52             break;
53 
54         //拓展节点
55         int next;
56         for(int i = -1;i == -1 || i == 1;i += 2) {
57             next = th + i * k[th];
58             if(next > N || next <= 0)
59                 continue;
60             if(!visited[next]) {
61                 Q.push(next);
62                 visited[next] = true;
63                 dis[next] = dis[th] + 1;
64             }
65         }
66 
67     }
68 
69     if(dis[v])
70         return dis[v];
71     else
72         return -1;
73 }
74 
75 bool Do() {
76     int s,v;
77     if(scanf("%d%d%d",&N,&s,&v),N == 0)
78         return false;
79     REP(N)
80         scanf("%d",&k[o + 1]);
81     printf("%d\n",BFS(s,v));
82     return true;
83 }
84 
85 int main() {
86     while(Do());
87     return 0;
88 }