34 lines
785 B
C++
34 lines
785 B
C++
// 112
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#include <bits/stdc++.h>
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using namespace std;
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int n, d;
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struct node
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{
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int x, y;
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double xl, xr;
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} is[1005];
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int main()
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{
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scanf("%d%d", &n, &d);
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for (int i = 1; i <= n; ++i)
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{
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scanf("%d%d", &is[i].x, &is[i].y);
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if (abs(is[i].y) > d)
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{
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puts("-1");
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return 0;
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}
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double len = sqrt(1.0 * d * d - 1.0 * is[i].y * is[i].y);
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is[i].xl = is[i].x - len, is[i].xr = is[i].x + len;
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}
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sort(is + 1, is + n + 1, [](const node &x, const node &y)
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{ return x.xr < y.xr; });
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int ans = 0;
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double now = -DBL_MAX;
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const double eps = 1e-10;
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for (int i = 1; i <= n; ++i)
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if (now + eps < is[i].xl)
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now = is[i].xr, ++ans;
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printf("%d\n", ans);
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return 0;
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} |