modified: 28.cpp

28.cpp

@@ -5,44 +5,30 @@ int n, d;
 struct node
 {
     int x, y;
-    int xl, xr;
-    const bool operator<(node b) const
-    {
-        return xr > b.xr;
-    }
+    double xl, xr;
 } is[1005];
 int main()
 {
     scanf("%d%d", &n, &d);
-    int minl = INT_MAX, maxl = INT_MIN;
     for (int i = 1; i <= n; ++i)
     {
         scanf("%d%d", &is[i].x, &is[i].y);
-        if (is[i].y > d)
+        if (abs(is[i].y) > d)
         {
             puts("-1");
             return 0;
         }
-        is[i].xl = is[i].x - sqrt(d * d - is[i].y * is[i].y);
-        is[i].xr = is[i].x + sqrt(d * d - is[i].y * is[i].y);
-        minl = min(minl, is[i].xl);
-        maxl = max(maxl, is[i].xr);
+        double len = sqrt(1.0 * d * d - 1.0 * is[i].y * is[i].y);
+        is[i].xl = is[i].x - len, is[i].xr = is[i].x + len;
     }
-    sort(is + 1, is + n + 1, [](node x, node y)
-         { return x.xl < y.xl; });
-    int ans = 0, now = 1;
-    int maxans = 0;
-    priority_queue<node> q;
-    for (int t = minl; t <= maxl; ++t)
-    {
-        while (!q.empty() && q.top().xr < t)
-            q.pop();
-        while (now <= n && is[now].xl >= t)
-        {
-            q.push(is[now++]);
-            maxans = max(maxans, (int)q.size());
-        }
-    }
-    printf("%d\n", maxans);
+    sort(is + 1, is + n + 1, [](const node &x, const node &y)
+         { return x.xr < y.xr; });
+    int ans = 0;
+    double now = -DBL_MAX;
+    const double eps = 1e-10;
+    for (int i = 1; i <= n; ++i)
+        if (now + eps < is[i].xl)
+            now = is[i].xr, ++ans;
+    printf("%d\n", ans);
     return 0;
 }