mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
74 lines
1.9 KiB
C++
74 lines
1.9 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <cmath>
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#include <algorithm>
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using namespace std;
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#define repf(i,a,b) for(int i=(a);i<=(b);i++)
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typedef long long ll;
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const int N = 21;
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const double PI = acos(-1.0);
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const double EPS = 1e-8;
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int t, n;
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struct Round {
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double x, y;
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double r;
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} r[N], ori;
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double dis(const Round &a, const Round &b) {
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return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
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}
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double insection_of_rounds(Round &a, Round &b) {
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double d = dis(a, b);
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if (d >= a.r + b.r)
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return 0;
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if (d <= fabs(a.r - b.r)) {
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double r = a.r < b.r ? a.r : b.r;
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return PI * r * r;
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}
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double ang1 = acos((a.r * a.r + d * d - b.r * b.r) / 2. / a.r / d);
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double ang2 = acos((b.r * b.r + d * d - a.r * a.r) / 2. / b.r / d);
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double ret = ang1 * a.r * a.r + ang2 * b.r * b.r - d * a.r * sin(ang1);
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return ret;
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}
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bool check(Round& ori) {
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repf (i, 0, n - 1) {
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if (insection_of_rounds(ori, r[i]) * 2 < PI * r[i].r * r[i].r)
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return false;
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}
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return true;
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};
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double bin(double l, double r, Round& ori) {
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double mid;
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while (fabs(l - r) >= EPS) {
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mid = (l + r) / 2;
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ori.r = mid;
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if (check(ori)) {
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r = mid;
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} else {
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l = mid + EPS;
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}
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}
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return mid;
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}
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int main() {
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scanf("%d", &t);
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while (t--) {
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scanf("%d", &n);
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repf (i, 0, n - 1) {
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scanf("%lf%lf%lf", &r[i].x, &r[i].y, &r[i].r);
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}
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double ans = 1e10;
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repf (i, 0, n - 1) {
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ori.x = r[i].x;
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ori.y = r[i].y;
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double right = 0;
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repf (j, 0, n - 1) {
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right = max(right, dis(ori, r[j]) + r[j].r);
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}
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ans = min(ans, bin(0, right, ori));
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}
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printf("%.4f\n", ans);
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}
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return 0;
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}
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