mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
105 lines
3.1 KiB
C++
105 lines
3.1 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<stdlib.h>
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#include<math.h>
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#include<algorithm>
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using namespace std;
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const int maxn = 1011;
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const double eps = 1e-8;
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const double pi = acos(-1.0);
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inline double dcmp(double x) {return (x > eps) - (x < -eps);}
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inline double Sqr(double x) {return x * x;}
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struct Point
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{
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double x, y, v;
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Point(){}
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Point(double x_, double y_){x = x_, y = y_;}
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double Dis(Point &b){return sqrt(Sqr(x - b.x) + Sqr(y - b.y));}
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};
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Point p[maxn], th;
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int n;
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void AngManage(double &x)
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{
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while(x + pi < -eps) x += pi + pi;
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while(x - pi > -eps) x -= pi + pi;
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}
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inline double CounterAng(double s, double e)
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{return e > s + eps ? e - s : pi + pi + e - s;}
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struct Cov
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{
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double s, e;
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void Read(double s_, double e_)
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{
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AngManage(s_), AngManage(e_);
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s = s_, e = e_;
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}
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bool operator<(const Cov &b)const
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{
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if(!dcmp(s - b.s)) return CounterAng(s, e) > CounterAng(b.s, b.e);
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return s < b.s;
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}
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} cover[maxn], cc[maxn];
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int main()
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{
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int t, i, j, k, ans, cnt;
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bool flag;
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for(scanf("%d", &t); t --; )
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{
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flag = false;
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scanf("%d", &n);
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scanf("%lf%lf%lf", &th.v, &th.x, &th.y);
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for(i = 0; i < n; ++ i)
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{
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scanf("%lf%lf%lf", &p[i].v, &p[i].x, &p[i].y);
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if(p[i].v > th.v + eps || !dcmp(p[i].Dis(th))) flag = true;
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}
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if(flag) {printf("1\n"); continue;}
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if(!dcmp(th.v)) {printf("0\n"); continue;}
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for(i = 0; i < n; ++ i)
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{
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double ang = atan2(p[i].y - th.y, p[i].x - th.x);
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if(p[i].v > th.v - eps)
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{
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cover[i].Read(ang - pi * 0.5, ang + pi * 0.5);
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continue;
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}
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double c = p[i].Dis(th);
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double T = sqrt(Sqr(c) / (Sqr(th.v) - Sqr(p[i].v)));
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double cs = acos(c / T / th.v);
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cover[i].Read(ang - cs, ang + cs);
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}
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sort(cover, cover + n);
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for(i = k = 1; i < n; ++ i)
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if(dcmp(cover[i].s - cover[i - 1].s)) cover[k ++] = cover[i];
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n = k;
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for(i = 0, ans = 0x3f3f3f3f; i < n; ++ i)
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{
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for(j = i, k = 0; ; j = (j + 1) % n)
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{
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cc[k].Read(cover[j].s - cover[i].s - pi, cover[j].e - cover[i].s - pi);
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if(cc[k].s > cc[k].e) cc[k].e = pi + pi;
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++ k;
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if(j == (i + n - 1) % n) break;
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}
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double now = -pi - pi, nex = -pi;
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flag = false;
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for(j = cnt = 0; j < n; ++ j)
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{
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if(cc[j].e < now + eps) continue;
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if(cc[j].s > nex + eps) break;
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if(cc[j].s > now + eps)
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{
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++ cnt;
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now = nex;
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}
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if(cc[j].e > nex + eps) nex = cc[j].e;
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if(nex > pi - eps) {flag = true; break;}
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}
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if(flag) ans = min(ans, cnt);
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}
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if(ans == 0x3f3f3f3f) ans = 0;
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printf("%d\n", ans);
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}
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return 0;
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}
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