91 lines
2.7 KiB
C++
91 lines
2.7 KiB
C++
#include <cstdlib>
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#include <cstring>
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#include <cstdio>
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#include <algorithm>
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#include <iostream>
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#include <cmath>
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using namespace std;
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const double eps = 1e-6;
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const double PI = acos(-1.0);
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double cx, cy, cr;
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inline int sign(double x) {
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return x < -eps ? -1 : x > eps ? 1 : 0;
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}
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struct Point {
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double x, y;
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Point (double xx = 0, double yy = 0) : x(xx), y(yy) {}
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Point operator - (const Point &ot) const {
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return Point(x - ot.x , y - ot.y);
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}
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double operator * (const Point &ot) const {
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return x * ot.x + y * ot.y;
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}
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double operator ^ (const Point &ot) const {
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return x * ot.y - y * ot.x;
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}
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bool operator < (const Point &ot) const {
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if (sign(x - ot.x)) {
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return sign(x - ot.x) < 0;
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} else {
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return sign(y - ot.y) < 0;
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}
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}
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void show() {
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printf("x = %.2f, y = %.2f\n", x, y);
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}
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};
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Point it, rp[4];
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double dist(const Point &a, const Point &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 dtoL(const Point &np, const Point &st, const Point &ed) {
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double ret;
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if (sign((ed-st)*(np-st)) > 0 && sign((st-ed)*(np-ed) > 0)) {
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ret = fabs((st-np)^(ed-np)) / dist(st, ed);
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} else {
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ret = min(dist(np, st), dist(np, ed));
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}
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return ret;
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}
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double dtoR(const Point &np) {
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double d1 = min(dtoL(np, rp[0], rp[1]), dtoL(np, rp[0], rp[2]));
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double d2 = min(dtoL(np, rp[1], rp[3]), dtoL(np, rp[2], rp[3]));
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return min(d1, d2);
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}
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double tsearch(double l, double r) {
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double delta;
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while (r - l >= eps) {
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delta = (r - l) / 3.0;
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Point Lp(cr*cos(l+delta), cr*sin(l+delta));
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Point Rp(cr*cos(r-delta), cr*sin(r-delta));
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double d1 = dist(it, Lp) + dtoR(Lp);
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double d2 = dist(it, Rp) + dtoR(Rp);
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if (sign(d1 - d2) > 0) {
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l += delta;
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} else {
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r -= delta;
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}
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}
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Point fp(cr*cos(r), cr*sin(r));
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return dist(it, fp) + dtoR(fp);
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}
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void solve() {
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printf("%.2f\n", min(tsearch(0, PI), tsearch(PI, 2*PI)));
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}
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int main() {
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while (scanf("%lf %lf", &it.x, &it.y), sign(it.x) | sign(it.y)) {
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scanf("%lf %lf %lf", &cx, &cy, &cr);
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it.x -= cx, it.y -= cy;
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scanf("%lf %lf", &rp[0].x, &rp[0].y);
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rp[0].x -= cx, rp[0].y -= cy;
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scanf("%lf %lf", &rp[1].x, &rp[1].y);
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rp[1].x -= cx, rp[1].y -= cy;
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rp[2].x = rp[0].x, rp[2].y = rp[1].y;
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rp[3].x = rp[1].x, rp[3].y = rp[0].y;
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sort(rp, rp+4);
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double t = sqrt(2.0) / 2;
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solve();
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}
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return 0;
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}
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