A strange lift （HDU1548）

HDU 1548 bfs（一维）
题意：电梯每层有一个不同的数字，例如第n层有个数字k，那么这一层只能上k层或下k层，

            但是不能低于一层或高于n层，给定起点与终点，要求出最少要按几次键。

#include <iostream>#include <cstdio>#include <cstring>#include <queue>using namespace std;#define N 210struct Node{    int time,flor;    Node(){}    Node(int _f,int _t){        flor = _f;time = _t;    }};queue<Node> q;int k[N],vis[N];int solve(int start,int end,int n){    while(!q.empty()) q.pop();    q.push(Node(start,0));    while(!q.empty()){        Node cur = q.front(); q.pop();        if(cur.flor==end) return cur.time;        int up = cur.flor + k[cur.flor];        int down = cur.flor - k[cur.flor];        int tim = cur.time + 1;        if(up<=n&&up>=1&&vis[up]==0){            q.push(Node(up,tim));            vis[up] = 1;        }        if(down<=n&&down>=1&&vis[down]==0){            q.push(Node(down,tim));            vis[down] = 1;        }    }    return -1;}void init(int n){    for(int i = 1;i<=n;i++)        vis[i] = k[i] = 0;}int main(){    int n,a,b;    while(~scanf("%d%d%d",&n,&a,&b)&&n){        init(n);        for(int i = 1;i<=n;i++) scanf("%d",&k[i]);        printf("%d\n",solve(a,b,n));    }    return 0;}