OJ-Problems-Source/HDOJ/2383_autoAC.cpp

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#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <queue>
using namespace std;
#define SZ(v) ((int)(v).size())
#define SQR(x) ((x) * (x))
const int maxint = -1u>>1;
const int maxn = 100 + 4;
const double eps = 1e-9;
const double inf = 1e10;
int sgn(double x) {
return (x > eps) - (x < -eps);
}
struct P {
double x, y;
P() {}
P(double _x, double _y): x(_x), y(_y) {}
bool operator != (const P &a) const {
return sgn(x - a.x) || sgn(y - a.y);
}
P operator + (const P &a) const {
return P(x + a.x, y + a.y);
}
P operator - (const P &a) const {
return P(x - a.x, y - a.y);
}
P operator * (const double &m) const {
return P(x * m, y * m);
}
double length() const {
return sqrt(SQR(x) + SQR(y));
}
P set(const double &m) const {
double len = length();
return P(x * m / len, y * m / len);
}
P turn_left() const {
return P(-y, x);
}
double dot(const P &a, const P &b) const {
return (a.x - x) * (b.x - x) + (a.y - y) * (b.y - y);
}
double cross(const P &a, const P &b) const {
return (a.x - x) * (b.y - y) - (a.y - y) * (b.x - x);
}
double dist(const P &a) const {
return sqrt(sqrdist(a));
}
double sqrdist(const P &a) const {
return SQR(a.x - x) + SQR(a.y - y);
}
void input() {
scanf("%lf%lf", &x, &y);
}
void output() const {
printf("%lf %lf\n", x, y);
}
};
struct node {
int x;
double val;
node() {}
node(int _x, double _val): x(_x), val(_val) {}
bool operator < (const node &a) const {
return val > a.val;
}
};
int n, m;
double r;
P cen[maxn];
vector<P> rec;
vector<vector<pair<int, double> > > v;
vector<double> dist;
vector<bool> used;
bool in_cir(const P &p) {
for (int i = 0; i < n; ++i) {
if (sgn(cen[i].dist(p) - r) < 0) return true;
}
return false;
}
void cir_cross(const P &c1, const P &c2) {
if (sgn(c1.dist(c2) - r * 2) > 0) return ;
P mid = (c1 + c2) * 0.5;
P dir = (c2 - c1).turn_left().set(sqrt(SQR(r) - c1.sqrdist(c2) / 4));
P p1 = mid + dir, p2 = mid - dir;
if (!in_cir(p1)) {
rec.push_back(p1);
}
if (p1 != p2 && !in_cir(p2)) {
rec.push_back(p2);
}
}
void spfa(int s) {
dist.resize(m);
used.resize(m);
for (int i = 0; i < m; ++i) {
dist[i] = inf;
used[i] = false;
}
priority_queue<node> que;
que.push(node(s, 0));
dist[s] = 0;
used[s] = false;
while (!que.empty()) {
node top = que.top();
que.pop();
used[top.x] = false;
for (int i = 0; i < (int)v[top.x].size(); ++i) {
int x = v[top.x][i].first;
if (dist[x] > dist[top.x] + v[top.x][i].second) {
dist[x] = dist[top.x] + v[top.x][i].second;
if (!used[x]) {
used[x] = true;
que.push(node(x, dist[x]));
}
}
}
}
}
int calc_init(const P &pt1) {
int res = 0;
for (int i = 0; i < n; ++i) {
if (sgn(pt1.dist(cen[i]) - r) <= 0) ++res;
}
return res;
}
void line_cross_cir(vector<pair<double, int> > &s, const P &p1, const P &p2, const P &c) {
double d = fabs(p1.cross(p2, c)) / p1.dist(p2);
if (sgn(d - r) > 0) return;
double s1 = sqrt(p1.sqrdist(c) - SQR(d));
if (sgn(p1.dot(c, p2)) < 0) s1 = -s1;
double s2 = sqrt(SQR(r) - SQR(d));
P pt1 = p1 + (p2 - p1).set(s1 - s2), pt2 = p1 + (p2 - p1).set(s1 + s2);
if (sgn(pt1.dot(p1, p2)) < 0) {
s.push_back(make_pair(pt1.dist(p1), 1));
}
if (sgn(pt2.dot(p1, p2)) < 0) {
s.push_back(make_pair(pt2.dist(p1), -1));
}
}
bool cmp(const pair<double, int> &x1, const pair<double, int> &x2) {
if (sgn(x1.first - x2.first) != 0) return x1.first < x2.first;
return x1.second > x2.second;
}
bool ok_line(const P &p1, const P &p2) {
P pt1 = p1 + (p2 - p1)*0.001;
vector<pair<double, int> > s;
for (int i = 0; i < n; ++i) {
line_cross_cir(s, pt1, p2, cen[i]);
}
sort(s.begin(), s.end());
int cnt = calc_init(pt1);
if (cnt == 0) return false;
for (int i = 0; i < (int)s.size(); ++i) {
cnt += s[i].second;
if (cnt == 0) return false;
}
return true;
}
int main() {
int t;
scanf("%d", &t);
while (t--) {
scanf("%lf%d", &r, &n);
P st, ed;
st.input();
ed.input();
for (int i = 0; i < n; ++i) {
cen[i].input();
}
rec.clear();
rec.push_back(st);
rec.push_back(ed);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < i; ++j) {
cir_cross(cen[i], cen[j]);
}
}
m = rec.size();
v.resize(m);
for (int i = 0; i < m; ++i) v[i].clear();
for (int i = 0; i < m; ++i) {
for (int j = 0; j < i; ++j) {
if (ok_line(rec[i], rec[j])) {
v[i].push_back(make_pair(j, rec[i].dist(rec[j])));
v[j].push_back(make_pair(i, rec[i].dist(rec[j])));
}
}
}
spfa(0);
if (sgn(dist[1] - inf) == 0) printf("-1\n");
else printf("%.12lf\n", dist[1]);
}
return 0;
}