mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
291 lines
7.4 KiB
C++
291 lines
7.4 KiB
C++
#include <set>
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#include <queue>
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#include <stack>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <iostream>
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#include <limits.h>
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#include <string.h>
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#include <string>
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#include <algorithm>
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#define MID(x,y) ( ( x + y ) >> 1 )
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#define L(x) ( x << 1 )
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#define R(x) ( x << 1 | 1 )
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#define FOR(i,s,t) for(int i=(s); i<(t); i++)
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#define BUG puts("here!!!")
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#define STOP system("pause")
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#define file_r(x) freopen(x, "r", stdin)
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#define file_w(x) freopen(x, "w", stdout)
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using namespace std;
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const int MAX = 1000;
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const double eps = 1e-6;
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const double inf = 1e50;
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struct point{
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double x, y;
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void get()
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{
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scanf("%lf%lf", &x, &y);
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}
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};
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bool dy(double x,double y) { return x > y + eps;}
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bool xy(double x,double y) { return x < y - eps;}
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bool dyd(double x,double y) { return x > y - eps;}
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bool xyd(double x,double y) { return x < y + eps;}
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bool dd(double x,double y) { return fabs( x - y ) < eps;}
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double disp2p(point a,point b)
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{
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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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bool operator==(point a, point b)
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{
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return dd(a.x, b.x) && dd(a.y, b.y);
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}
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typedef struct NODE{
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int to;
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double len;
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NODE *next;
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}NODE;
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NODE *p[MAX],node[MAX*MAX];
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struct circle{
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point c;
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double r;
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};
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circle c[MAX];
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int cou;
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void init()
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{
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cou = 0;
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memset(p, 0, sizeof(p));
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}
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void Add(int from,int to,double len)
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{
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node[cou].next = p[from];
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node[cou].to = to;
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node[cou].len = len;
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p[from] = &node[cou++];
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}
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queue<int> q;
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double SPFA_List(int from,int to,int n)
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{
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while( !q.empty() ) q.pop();
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double dis[MAX];
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bool inq[MAX];
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for(int i=0; i<n; i++)
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dis[i] = inf;
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memset(inq,false,sizeof(inq));
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dis[from] = 0;
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q.push(from);
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inq[from] = 1;
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while( !q.empty() )
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{
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int now = q.front();
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q.pop();
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inq[now] = false;
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NODE *head = p[now];
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while( head != NULL )
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{
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int v = head->to;
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double len = head->len;
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if( dy(dis[v], dis[now] + len) )
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{
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dis[v] = dis[now] + len;
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if( !inq[v] )
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{
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inq[v] = true;
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q.push(v);
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}
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}
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head = head->next;
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}
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}
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if( dd(dis[to], inf) ) return -1;
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return dis[to];
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}
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point l2l_inst_p(point u1,point u2,point v1,point v2)
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{
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point ans = u1;
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double t = ((u1.x - v1.x)*(v1.y - v2.y) - (u1.y - v1.y)*(v1.x - v2.x))/
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((u1.x - u2.x)*(v1.y - v2.y) - (u1.y - u2.y)*(v1.x - v2.x));
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ans.x += (u2.x - u1.x)*t;
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ans.y += (u2.y - u1.y)*t;
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return ans;
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}
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void l2c_inst_p(point c,double r,point l1,point l2,point &p1,point &p2)
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{
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point p = c;
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double t;
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p.x += l1.y - l2.y;
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p.y += l2.x - l1.x;
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p = l2l_inst_p(p,c,l1,l2);
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t = sqrt(r*r - disp2p(p,c)*disp2p(p,c))/disp2p(l1,l2);
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p1.x = p.x + (l2.x - l1.x)*t;
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p1.y = p.y + (l2.y - l1.y)*t;
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p2.x = p.x - (l2.x - l1.x)*t;
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p2.y = p.y - (l2.y - l1.y)*t;
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}
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void c2c_inst_p(point c1,double r1,point c2,double r2,point &p1,point &p2)
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{
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point u,v;
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double t;
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t = (1 + (r1*r1 - r2*r2)/disp2p(c1,c2)/disp2p(c1,c2))/2;
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u.x = c1.x + (c2.x - c1.x)*t;
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u.y = c1.y + (c2.y - c1.y)*t;
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v.x = u.x + c1.y - c2.y;
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v.y = u.y - c1.x + c2.x;
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l2c_inst_p(c1,r1,u,v,p1,p2);
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}
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bool c2c_tangent(point a,double r1,point b,double r2)
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{
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if( dd(disp2p(a,b),r1+r2) || dd(disp2p(a,b),fabs(r1-r2)) )
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return true;
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return false;
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}
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point c2c_tangent_p(point a,double r1,point b,double r2)
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{
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point t;
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if( dd(disp2p(a,b),r1 + r2) )
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{
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t.x = (r1*b.x + r2*a.x)/(r1 + r2);
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t.y = (r1*b.y + r2*a.y)/(r1 + r2);
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return t;
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}
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t.x = (r1*b.x - r2*a.x)/(r1 - r2);
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t.y = (r1*b.y - r2*a.y)/(r1 - r2);
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return t;
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}
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point g[MAX];
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bool f[MAX][MAX];
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double crossProduct(point a,point b,point c)
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{
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return (c.x - a.x)*(b.y - a.y) - (b.x - a.x)*(c.y - a.y);
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}
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double disp2l(point a,point l1,point l2)
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{
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return fabs( crossProduct(a,l1,l2) )/disp2p(l1,l2);
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}
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bool onSegment(point a, point b, point c)
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{
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if( dd(crossProduct(a,b,c),0.0) && dyd(c.x,min(a.x,b.x)) &&
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xyd(c.x,max(a.x,b.x)) && dyd(c.y,min(a.y,b.y)) && xyd(c.y,max(a.y,b.y)) )
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return true;
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return false;
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}
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bool cmp(point a, point b)
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{
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if( dd(a.x, b.x) ) return xy(a.y, b.y);
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return xy(a.x, b.x);
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}
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point tp[MAX];
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bool check(int cnt, int n)
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{
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FOR(i, 1, cnt)
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{
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point tt;
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tt.x = (tp[i].x + tp[i-1].x)/2;
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tt.y = (tp[i].y + tp[i-1].y)/2;
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bool f = false;
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FOR(k, 0, n)
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if( xyd(disp2p(c[k].c, tt), c[k].r) )
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{
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f = true;
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break;
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}
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if( !f )
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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 solve(int n)
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{
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int l = 0;
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int s = 0, t = n-1;
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FOR(i, 0, n)
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g[l++] = c[i].c;
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FOR(i, 0, n)
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{
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FOR(k, i+1, n)
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{
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if( dy(disp2p(c[i].c, c[k].c), c[i].r + c[k].r)
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|| c[i].c == c[k].c )
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continue;
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if( c2c_tangent(c[i].c, c[i].r, c[k].c, c[k].r) )
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{
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point tt = c2c_tangent_p(c[i].c, c[i].r, c[k].c, c[k].r);
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g[l++] = tt;
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continue;
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}
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point t1, t2;
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c2c_inst_p(c[i].c, c[i].r, c[k].c, c[k].r, t1, t2);
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g[l++] = t1;
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g[l++] = t2;
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}
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}
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memset(f, false, sizeof(f));
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int tmp[MAX];
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FOR(i, 0, n)
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{
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int cnt = 0;
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FOR(k, 0, l)
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if( xyd(disp2p(c[i].c, g[k]), c[i].r) )
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tmp[cnt++] = k;
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FOR(k, 0, cnt)
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FOR(j, k+1, cnt)
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{
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int x = tmp[k], y = tmp[j];
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if( f[x][y] ) continue;
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double dis = disp2p(g[x], g[y]);
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Add(x, y, dis);
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Add(y, x, dis);
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f[x][y] = f[y][x] = true;
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}
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}
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FOR(i, 0, l)
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FOR(k, i+1, l)
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{
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if( f[i][k] ) continue;
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int cnt = 0;
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tp[cnt++] = g[i];
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tp[cnt++] = g[k];
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FOR(j, 0, n)
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if( xyd(disp2l(c[j].c, g[i], g[k]),c[j].r) )
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{
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point t1, t2;
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l2c_inst_p(c[j].c, c[j].r, g[i], g[k], t1, t2);
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if( onSegment(g[i], g[k], t1) )
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tp[cnt++] = t1;
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if( onSegment(g[i], g[k], t2) )
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tp[cnt++] = t2;
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}
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sort(tp, tp+cnt, cmp);
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if( check(cnt, n) )
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{
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Add(i, k, disp2p(g[i], g[k]));
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Add(k, i, disp2p(g[k], g[i]));
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}
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}
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return SPFA_List(s, t, l);
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}
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int main()
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{
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int ncases, n, ind = 1;
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scanf("%d", &ncases);
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while( ncases-- )
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{
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scanf("%d", &n);
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init();
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FOR(i, 0, n)
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{
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c[i].c.get();
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scanf("%lf", &c[i].r);
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}
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double ans = solve(n);
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printf("Case %d: ",ind++);
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if( ans < -eps )
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puts("No such path.");
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else
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printf("%.4lf\n", ans);
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}
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return 0;
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}
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