hdu 1548 A strange lift

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=1548
简单的bfs。。。

#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<queue>#include<map>using std::cin;using std::cout;using std::endl;using std::find;using std::sort;using std::map;using std::pair;using std::vector;using std::queue;#define pb(e) push_back(e)#define sz(c) (int)(c).size()#define mp(a, b) make_pair(a, b)#define all(c) (c).begin(), (c).end()#define iter(c) decltype((c).begin())#define cls(arr,val) memset(arr,val,sizeof(arr))#define cpresent(c, e) (find(all(c), (e)) != (c).end())#define rep(i, n) for (int i = 0; i < (int)(n); i++)#define tr(c, i) for (iter(c) i = (c).begin(); i != (c).end(); ++i)const int Max_N = 210;const int dx[] = { -1, 1 };typedef unsigned long long ull;bool vis[Max_N];int N, A, B, arr[Max_N];struct Node {    int x, s;    Node(int i = 0, int j = 0) :x(i), s(j) {}};void bfs() {    cls(vis, 0);    queue<Node> que;    que.push(Node(A, 0));    vis[A] = true;    while (!que.empty()) {        Node tp = que.front(); que.pop();        if (tp.x == B) { printf("%d\n", tp.s); return; }        rep(i, 2) {            int nx = dx[i] * arr[tp.x] + tp.x;            if (nx < 0 || nx > N || vis[nx]) continue;            que.push(Node(nx, tp.s + 1));            vis[nx] = true;        }    }    puts("-1");}int main() {#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    while (~scanf("%d", &N) && N) {        scanf("%d %d", &A, &B);        rep(i, N) scanf("%d", &arr[i + 1]);        bfs();    }    return 0;}