A New Ground Heating Device UVALive - 7675 （圆的面积交）
A New Ground Heating Device
终于补了这道圆的面积交...
虽然还没仔细看模板，先收着吧=_=
等打完区域赛好好琢磨一下～
1 #include <bits/stdc++.h> 2 using namespace std; 3 const double eps = 1e-8; 4 const int maxn = 210; 5 const double pi = acos(-1.0); 6 double area[maxn]; 7 8 #define sqr(x) (x)*(x) 9 int dcmp(double x) { 10 if (x < -eps) return -1; else return x > eps; 11 } 12 struct cp { 13 double x, y, r, angle; 14 int d; 15 cp(){} 16 cp(double xx, double yy, double ang = 0, int t = 0) { 17 x = xx; y = yy; angle = ang; d = t; 18 } 19 void get() { 20 scanf("%lf%lf%lf", &x, &y, &r); 21 d = 1; 22 } 23 }cir[maxn], tp[maxn * 2]; 24 double dis(cp a, cp b) { 25 return sqrt(sqr(a.x - b.x) + sqr(a.y - b.y)); 26 } 27 double cross(cp p0, cp p1, cp p2) { 28 return (p1.x - p0.x) * (p2.y - p0.y) - (p1.y - p0.y) * (p2.x - p0.x); 29 } 30 int CirCrossCir(cp p1, double r1, cp p2, double r2, cp &cp1, cp &cp2) { 31 double mx = p2.x - p1.x, sx = p2.x + p1.x, mx2 = mx * mx; 32 double my = p2.y - p1.y, sy = p2.y + p1.y, my2 = my * my; 33 double sq = mx2 + my2, d = -(sq - sqr(r1 - r2)) * (sq - sqr(r1 + r2)); 34 if (d + eps < 0) return 0; if (d < eps) d = 0; else d = sqrt(d); 35 double x = mx * ((r1 + r2) * (r1 - r2) + mx * sx) + sx * my2; 36 double y = my * ((r1 + r2) * (r1 - r2) + my * sy) + sy * mx2; 37 double dx = mx * d, dy = my * d; sq *= 2; 38 cp1.x = (x - dy) / sq; cp1.y = (y + dx) / sq; 39 cp2.x = (x + dy) / sq; cp2.y = (y - dx) / sq; 40 if (d > eps) return 2; else return 1; 41 } 42 bool circmp(const cp& u, const cp& v) { 43 return dcmp(u.r - v.r) < 0; 44 } 45 bool cmp(const cp& u, const cp& v) { 46 if (dcmp(u.angle - v.angle)) return u.angle < v.angle; 47 return u.d > v.d; 48 } 49 double calc(cp cir, cp cp1, cp cp2) { 50 double ans = (cp2.angle - cp1.angle) * sqr(cir.r) 51 - cross(cir, cp1, cp2) + cross(cp(0, 0), cp1, cp2); 52 return ans / 2; 53 } 54 void CirUnion(cp cir[], int n) { 55 cp cp1, cp2; 56 sort(cir, cir + n, circmp); 57 for (int i = 0; i < n; ++i) 58 for (int j = i + 1; j < n; ++j) 59 if (dcmp(dis(cir[i], cir[j]) + cir[i].r - cir[j].r) <= 0) 60 cir[i].d++; 61 for (int i = 0; i < n; ++i) { 62 int tn = 0, cnt = 0; 63 for (int j = 0; j < n; ++j) { 64 if (i == j) continue; 65 if (CirCrossCir(cir[i], cir[i].r, cir[j], cir[j].r, 66 cp2, cp1) < 2) continue; 67 cp1.angle = atan2(cp1.y - cir[i].y, cp1.x - cir[i].x); 68 cp2.angle = atan2(cp2.y - cir[i].y, cp2.x - cir[i].x); 69 cp1.d = 1; tp[tn++] = cp1; 70 cp2.d = -1; tp[tn++] = cp2; 71 if (dcmp(cp1.angle - cp2.angle) > 0) cnt++; 72 } 73 tp[tn++] = cp(cir[i].x - cir[i].r, cir[i].y, pi, -cnt); 74 tp[tn++] = cp(cir[i].x - cir[i].r, cir[i].y, -pi, cnt); 75 sort(tp, tp + tn, cmp); 76 int p, s = cir[i].d + tp[0].d; 77 for (int j = 1; j < tn; ++j) { 78 p = s; s += tp[j].d; 79 area[p] += calc(cir[i], tp[j - 1], tp[j]); 80 } 81 } 82 } 83 84 int X[maxn], Y[maxn]; 85 double Z[maxn]; 86 87 int n, k, w, s; 88 int ck(double x){ 89 memset(cir, 0, sizeof(cir)); 90 for(int i = 0; i < n; i++){ 91 cir[i].x = X[i]; 92 cir[i].y = Y[i]; 93 cir[i].r = w * 1.0 / Z[i] / sqrt(sqr(X[i]) + sqr(Y[i]) + sqr(x)); 94 cir[i].d = 1; 95 } 96 memset(area, 0, sizeof(area)); 97 CirUnion(cir, n); 98 if(dcmp(area[k] - s) >= 0) return 1; 99 return 0; 100 } 101 int main(){ 102 int t; 103 //freopen("in.txt", "r", stdin); 104 scanf("%d", &t); 105 while(t--){ 106 scanf("%d %d %d %d", &n, &w, &k, &s); 107 for(int i = 0; i < n; i++){ 108 scanf("%d %d %lf", &X[i], &Y[i], &Z[i]); 109 } 110 double L = 0, R = 500; 111 if(ck(500)) { 112 puts("Oops!"); 113 }else if(!ck(0)) { 114 puts("No solution!"); 115 }else { 116 while(R - L > 1e-6) { 117 double m = (R + L) / 2; 118 if(ck(m)) L = m; 119 else R = m; 120 } 121 printf("%.4lf\n", R); 122 } 123 int ty; 124 while(scanf("%d", &ty) != EOF) cout<<area[ty]<<endl; 125 } 126 return 0; 127 }
