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@@ -0,0 +1,51 @@
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+#include <algorithm>
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+#include <cmath>
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+#include <cstdio>
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+#include <limits>
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+
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+using namespace std;
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+
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+const double eps = 1e-6;
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+
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+int n, d, id = 0;
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+
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+struct Island {
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+ double rs;
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+ double re;
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+ void set(int x, int y) {
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+ double dx = sqrt(double(d) * d - double(y) * y);
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+ rs = x - dx;
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+ re = x + dx;
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+ }
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+ bool operator<(const Island that) { return this->rs < that.rs; }
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+};
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+
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+int main() {
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+ Island is[1000];
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+ while (scanf("%d %d", &n, &d) != EOF && (n != 0 || d != 0)) {
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+ int x, y, cnt = 0;
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+ for (int i = 0; i < n; i++) {
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+ scanf("%d %d", &x, &y);
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+ if (d < fabs(y)) { // !!!y maybe negative
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+ cnt = -1;
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+ continue;
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+ }
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+ is[i].set(x, y);
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+ }
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+ if (cnt == 0) {
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+ sort(is, is + n);
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+ // Avoid overflow, use -max instead of min
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+ double end = -numeric_limits<double>::max();
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+ for (int i = 0; i < n; i++) {
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+ if (is[i].rs - end > eps) {
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+ cnt++;
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+ end = is[i].re;
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+ } else if (end - is[i].re > eps) {
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+ end = is[i].re;
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+ }
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+ }
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+ }
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+ printf("Case %d: %d\n", ++id, cnt);
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+ }
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+ return 0;
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+}
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