delete pics to save space

2.10382.cpp

@@ -0,0 +1,47 @@
+#include<bits/stdc++.h>
+using namespace std;
+const int maxn=10005;
+struct Circle
+{
+	double p,r,d;
+};
+int n;
+double l,w;
+Circle c[maxn];
+bool cmp(const Circle &a,const Circle &b)
+{ return a.p-a.d<b.p-b.d; }
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d%lf%lf",&n,&l,&w)==3)
+	{
+		for(int i=0;i<n;i++)
+		{
+			scanf("%lf%lf",&c[i].p,&c[i].r);
+			if(w/2>=c[i].r)
+			{
+				n--;
+				i--;
+				continue;
+			}
+			c[i].d=sqrt(c[i].r*c[i].r-w*w/4);
+		}
+		sort(c,c+n,cmp);
+		double now=0.0,maxd;
+		int res=0,p=0;
+		while(now<l&&p<n)
+		{
+			maxd=now;
+			while(p<n&&c[p].p-c[p].d<=now)
+				maxd=max(maxd,c[p].p+c[p].d),p++;
+			res++;
+			if(maxd>now) now=maxd;
+			else break;
+		}
+		if(now<l) res=-1;
+		printf("%d\n",res);
+	}
+	return 0;
+}