106 lines
3.2 KiB
C++
106 lines
3.2 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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const int maxn = 555;
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const int maxisn = 10;
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const double eps = 1e-8;
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const double pi = acos(-1.0);
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int dcmp(double x)
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{
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if(x > eps) return 1;
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return x < -eps ? -1 : 0;
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}
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inline double min(double a, double b)
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{return a < b ? a : b;}
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inline double max(double a, double b)
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{return a > b ? a : b;}
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inline double Sqr(double x)
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{return x * x;}
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struct Point
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{
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double x, y;
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Point(){x = y = 0;}
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Point(double a, double b)
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{x = a, y = b;}
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inline Point operator-(const Point &b)const
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{return Point(x - b.x, y - b.y);}
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inline Point operator+(const Point &b)const
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{return Point(x + b.x, y + b.y);}
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inline double dot(const Point &b)const
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{return x * b.x + y * b.y;}
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inline double cross(const Point &b, const Point &c)const
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{return (b.x - x) * (c.y - y) - (c.x - x) * (b.y - y);}
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};
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Point LineCross(const Point &a, const Point &b, const Point &c, const Point &d)
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{
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double u = a.cross(b, c), v = b.cross(a, d);
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return Point((c.x * v + d.x * u) / (u + v), (c.y * v + d.y * u) / (u + v));
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}
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double PolygonArea(Point p[], int n)
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{
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if(n < 3) return 0.0;
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double s = p[0].y * (p[n - 1].x - p[1].x);
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p[n] = p[0];
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for(int i = 1; i < n; ++ i)
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s += p[i].y * (p[i - 1].x - p[i + 1].x);
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return fabs(s * 0.5);
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}
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double CPIA(Point a[], Point b[], int na, int nb)//ConvexPolygonIntersectArea
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{
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Point p[maxisn], tmp[maxisn];
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int i, j, tn, sflag, eflag;
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a[na] = a[0], b[nb] = b[0];
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memcpy(p, b, sizeof(Point) * (nb + 1));
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for(i = 0; i < na && nb > 2; ++ i)
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{
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sflag = dcmp(a[i].cross(a[i + 1], p[0]));
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for(j = tn = 0; j < nb; ++ j, sflag = eflag)
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{
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if(sflag >= 0) tmp[tn ++] = p[j];
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eflag = dcmp(a[i].cross(a[i + 1], p[j + 1]));
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if((sflag ^ eflag) == -2)
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tmp[tn ++] = LineCross(a[i], a[i + 1], p[j], p[j + 1]);
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}
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memcpy(p, tmp, sizeof(Point) * tn);
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nb = tn, p[nb] = p[0];
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}
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if(nb < 3) return 0.0;
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return PolygonArea(p, nb);
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}
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double SPIA(Point a[], Point b[], int na, int nb)//SimplePolygonIntersectArea
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{
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int i, j;
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Point t1[4], t2[4];
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double res = 0, if_clock_t1, if_clock_t2;
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a[na] = t1[0] = a[0], b[nb] = t2[0] = b[0];
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for(i = 2; i < na; ++ i)
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{
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t1[1] = a[i - 1], t1[2] = a[i];
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if_clock_t1 = dcmp(t1[0].cross(t1[1], t1[2]));
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if(if_clock_t1 < 0) std::swap(t1[1], t1[2]);
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for(j = 2; j < nb; ++ j)
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{
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t2[1] = b[j - 1], t2[2] = b[j];
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if_clock_t2 = dcmp(t2[0].cross(t2[1], t2[2]));
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if(if_clock_t2 < 0) std::swap(t2[1], t2[2]);
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res += CPIA(t1, t2, 3, 3) * if_clock_t1 * if_clock_t2;
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}
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}
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return PolygonArea(a, na) + PolygonArea(b, nb) - res;
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}
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Point p1[maxn], p2[maxn];
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int n1, n2;
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int main()
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{
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int i;
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while(scanf("%d%d", &n1, &n2) != EOF)
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{
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for(i = 0; i < n1; ++ i) scanf("%lf%lf", &p1[i].x, &p1[i].y);
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for(i = 0; i < n2; ++ i) scanf("%lf%lf", &p2[i].x, &p2[i].y);
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printf("%.2f\n", SPIA(p1, p2, n1, n2) + eps);
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}
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return 0;
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}
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