bzoj1615 [Usaco2008 Mar]The Loathesome Hay Baler麻烦的干草打包机
感觉自己像个智障
直接bfs
然而读入没判负号查了半小时。。
1 #include<cstdio> 2 #include<cctype> 3 #include<cmath> 4 #include<cstring> 5 #include<algorithm> 6 using namespace std; 7 #define maxn 1100 8 #define eps 1e-8 9 int n,tx,ty; 10 int st,ed; 11 int x[maxn],y[maxn],r[maxn]; 12 double v[maxn],ans; 13 bool vis[maxn]; 14 int q[maxn*5]; 15 int fa[maxn]; 16 inline int read(){ 17 int x=0,f=1;char ch=getchar(); 18 while (!isdigit(ch)) { 19 if (ch=='-') f=-1; 20 ch=getchar(); 21 } 22 while (isdigit(ch)) { 23 x=x*10+ch-'0'; 24 ch=getchar(); 25 } 26 return x*f; 27 } 28 inline bool ok(int i,int j){ 29 double dis=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]); 30 double d2=r[i]+r[j]; 31 if (dis==d2*d2) return 1; 32 else return 0; 33 } 34 inline void bfs(){ 35 int head=0,tail=1; 36 q[head]=st;v[st]=10000;vis[st]=1; 37 while (head<tail){ 38 int now=q[head];head++; 39 for (int i=1;i<=n;i++){ 40 if (!vis[i]&&ok(now,i)){ 41 vis[i]=1,q[tail++]=i; 42 fa[i]=now; 43 v[i]=v[now]/r[i]*r[now]; 44 if (i==ed) return; 45 } 46 } 47 48 } 49 } 50 int main(){ 51 n=read(),tx=read(),ty=read(); 52 for (int i=1;i<=n;i++){ 53 x[i]=read(),y[i]=read(),r[i]=read(); 54 if (x[i]==0&&y[i]==0) st=i; 55 if (x[i]==tx&&y[i]==ty) ed=i; 56 } 57 memset(v,0,sizeof(v)); 58 memset(vis,0,sizeof(vis)); 59 memset(q,0,sizeof(q)); 60 memset(fa,0,sizeof(fa)); 61 bfs(); 62 ans=0; 63 for (int i=ed;i;i=fa[i]) 64 ans+=v[i]; 65 printf("%d\n",(int)ans); 66 return 0; 67 }
