POJ 3608 Bridge Across Islands (packet shortest distance between two convex rotational jam +)

Title: Portal

 

Classic title

 

Most of the code reference: kuangbin

 

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
#include <map>
#include <vector>
#include <set>
#include <string>
#include <math.h>
#define LL long long
#define mem(i, j) memset(i, j, sizeof(i))
#define rep(i, j, k) for(int i = j; i <= k; i++)
#define dep(i, j, k) for(int i = k; i >= j; i--)
#define pb push_back
#definethe make_pair the make
 #define INF INT_MAX
 #define INF LLONG_MAX
 #define the PI ACOS (-1)
 the using  namespace STD; 

const  int N = 5E5 + . 5 ; 

struct Point {
     Double X, Y; 
    Point ( Double X = 0 , Double Y = 0 ) : X (X), Y (Y) {} /// constructor 
}; 

typedef point the vector; 
/// vector + vector = vector + vector = vector point 
the vector operator + (the vector A, the vector B) { return the vector (+ Ax of Bx, Ay + By);}
/// point - point = vector of 
the Vector operator - (Point A, Point B) { return the Vector (Ax of - Bx, Ay - By);}
 /// vector * vector number = 
the Vector operator * (the Vector A, Double P) { return the vector (Ax of P *, Ay * P);}
 /// vector / vector number = 
the vector operator / (the vector A, Double P) { return the vector (Ax of / P, Ay / P);} 

const  Double EPS = 1E- . 8 ;
 int dCMP ( Double X) {
     IF (FABS (X) <EPS) return 0; else return x < 0 ? -1 : 1;
}

bool operator < (const Point& a, const Point& b) {
    return a.x == b.x ? a.y < b.y : a.x < b.x;
}

bool operator == (const Point& a, const Point &b) {
    return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;
}

double Dot(Vector A, Vector B) { return A.x*B.x + A.y*B.y; } // dot product 
Double the Length (the Vector A) { return sqrt ( 1.0 * Dot (A, A));} /// calculated vector length 
Double Angle (the Vector A, the Vector B) { return ACOS (Dot (A, B ) / the Length (A) / the Length (B));} /// vector A, B angle 
Double Cross (the vector A, the vector B) { return Ax of * By - Ay * Bx;} /// cross product 

int , ConvexHull (Point * P, int n-, Point * CH) { 
    Sort (P, P + n-);
     int m = 0 ; 
    REP (I, 0 , n-- . 1 ) {
        while(m > 1 && Cross(ch[m - 1] - ch[m - 2], p[i] - ch[m - 2]) <= 0) m--;
        ch[m++] = p[i];
    }
    int k = m;
    dep(i, 0, n - 2) {
        while(m > k && Cross(ch[m - 1] - ch[m - 2], p[i] - ch[m - 2]) <= 0) m--;
        ch[m++] = p[i];
    }
    if(n > 1) m--;
    return m; 
} 

Double the PTS (Point p, Point A, Point B) { /// find the point p to the line segment AB shortest distance 
    IF (A == B) return the Length (p - A); 
    Point V1 = B - A , V2 = P - A, V3 = P - B;
     IF (dCMP (Dot (V1, V2)) < 0 ) return the Length (V2);
     the else  IF (dCMP (Dot (V1, V3))> 0 ) return the Length (V3);
     the else  return FABS (Cross (V1, V2)) / the Length (V1); 
} 
/ * distance parallel to the line segment a1a2 b1b2 and * / 
Double DS(Point a1, Point a2, Point b1, Point b2) {
    return min(PTS(b1, a1, a2), min(PTS(b2, a1, a2), min(PTS(a1, b1, b2), PTS(a2, b1, b2))));
}

/* 得到向量 a1a2 和 b1b2 的位置关系 */
double Get_angle(Point a1, Point a2, Point b1, Point b2) {
    Point t = b1 - (b2 - a1);
    return Cross(a2 - a1, t - a1);
}

double Rotating_calipers(Point P[], int n, Point Q[], int m) {
    int posp = 0, posq = 0;

    rep(i, 0, n - 1) if(dcmp(P[i].y - P[posp].y) < 0) posp = i;
    rep(i, 0, m - 1) if(dcmp(Q[i].y - Q[posq].y) > 0) posq = i;

    double tmp, ans = 1e99;

    rep(i, 0, n - 1) {
        while(dcmp(tmp = Get_angle(P[posp], P[(posp + 1) % n], Q[posq], Q[(posq + 1) % m])) < 0)
            posq = (posq + 1) % m;
        if(dcmp(tmp) == 0)
            ans = min(ans, DS(P[posp], P[(posp + 1) % n], Q[posq], Q[(posq + 1) % m]));
        else
            ans = min(ans, PTS(Q[posq], P[posp], P[(posp + 1) % n]));
        posp = (posp + 1) % n;
    }

    return ans;
}

Point P[N], Q[N], p[N], q[N];

int main() {
    int n, m;
    while(scanf("%d %d", &n, &m) && n + m) {

        rep(i, 0, n - 1) scanf("%lf %lf", &p[i].x, &p[i].y);
        rep(i, 0, m - 1) scanf("%lf %lf", &q[i].x, &q[i].y);

        n = ConvexHull(p, n, P);
        m = ConvexHull(q, m, Q);

        double ans = min(Rotating_calipers(P, n, Q, m), Rotating_calipers(Q, m, P, n));

        printf("%.5f\n", ans);

    }
    return 0;
}