HDU-1548-A strange lift

HDU-1548-A strange lift

http://acm.hdu.edu.cn/showproblem.php?pid=1548

基本的BFS，上下兩個方向搜尋

#include<iostream>#include<cstdio>#include<cstring>#include<cstdlib>#include<queue>using namespace std;int n;int visit[205];int num[205];struct node{int x;int step;};int go(int x){if(1<=x&&x<=n)return 1;return 0;}int bfs(int a,int b){queue<node>q;node st,ed;int t;st.x=a;st.step=0;q.push(st);memset(visit,0,sizeof(visit));visit[st.x]=1;while(!q.empty()){st=q.front();q.pop();if(st.x==b)return st.step;t=st.x+num[st.x];if(go(t)&&!visit[t]){visit[t]=1;ed.x=t;ed.step=st.step+1;q.push(ed);}t=st.x-num[st.x];if(go(t)&&!visit[t]){visit[t]=1;ed.x=t;ed.step=st.step+1;q.push(ed);}}return -1;}int main(){int i,ans;int a,b;while(scanf("%d",&n),n){scanf("%d%d",&a,&b);        for(i=1;i<=n;i++)scanf("%d",&num[i]);if(a==b){printf("0\n");continue;}ans=bfs(a,b);printf("%d\n",ans);}return 0;}