delete pics to save space

2.11853.cpp

@@ -0,0 +1,55 @@
+#include<cstdio>
+#include<cmath>
+#include<cstring>
+#include<algorithm>
+using namespace std;
+const int N=1010;
+struct Circle
+{
+	int x,y,r;
+	inline void read(){ scanf("%d%d%d",&x,&y,&r); }
+}c[N];
+double ans1,ans2;
+int n,vis[N];
+inline bool can(const Circle &a,const Circle &b)
+{
+	int dx=a.x-b.x;
+	int dy=a.y-b.y;
+	return dx*dx+dy*dy<=(a.r+b.r)*(a.r+b.r);
+}
+bool dfs(int u)
+{
+	vis[u]=1;
+	if(c[u].y<=c[u].r) return false;
+	if(c[u].x<=c[u].r) ans1=min(ans1,c[u].y-sqrt(c[u].r*c[u].r-c[u].x*c[u].x));
+	if(1000<=c[u].x+c[u].r)
+		ans2=min(ans2,c[u].y-sqrt(c[u].r*c[u].r-(1000-c[u].x)*(1000-c[u].x)));
+	for(int i=0;i<n;i++)
+		if(!vis[i]&&can(c[u],c[i])&&!dfs(i))
+			return false;
+	return true;
+}
+void solve()
+{
+	ans1=ans2=1000;
+	for(int i=0;i<n;i++)
+		if(!vis[i]&&c[i].y+c[i].r>=1000&&!dfs(i))
+		{
+			puts("IMPOSSIBLE");
+			return;
+		}
+	printf("0.00 %.2lf 1000.00 %.2lf\n",ans1,ans2);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d",&n)==1)
+	{
+		memset(vis,0,sizeof(vis));
+		for(int i=0;i<n;i++) c[i].read();
+		solve();
+	}
+	return 0;
+}