POJ3449 正方形已知对角线两点坐标，求另外两点
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已知对角线两点(x0,y0) (x1,y1)
x1+x3 = x0+x2;
x1-x3 = y2-y0;
y1+y3 = y0-y2;
y1-y3 = x0-x2;
1 #include <iostream> 2 #include <stdio.h> 3 #include <string.h> 4 #include <algorithm> 5 #include <queue> 6 #include <map> 7 #include <vector> 8 #include <set> 9 #include <string> 10 #include <math.h> 11 12 using namespace std; 13 const double eps = 1e-8; 14 int sgn(double x) 15 { 16 if(fabs(x) < eps)return 0; 17 if(x < 0)return -1; 18 else return 1; 19 } 20 struct Point 21 { 22 double x,y; 23 Point(){} 24 Point(double _x,double _y) 25 { 26 x = _x;y = _y; 27 } 28 Point operator -(const Point &b)const 29 { 30 return Point(x - b.x,y - b.y); 31 } 32 //叉积 33 double operator ^(const Point &b)const 34 { 35 return x*b.y - y*b.x; 36 } 37 //点积 38 double operator *(const Point &b)const 39 { 40 return x*b.x + y*b.y; 41 } 42 }; 43 struct Line 44 { 45 Point s,e; 46 Line(){} 47 Line(Point _s,Point _e) 48 { 49 s = _s;e = _e; 50 } 51 }; 52 //*判断线段相交 53 bool inter(Line l1,Line l2) 54 { 55 return 56 max(l1.s.x,l1.e.x) >= min(l2.s.x,l2.e.x) && 57 max(l2.s.x,l2.e.x) >= min(l1.s.x,l1.e.x) && 58 max(l1.s.y,l1.e.y) >= min(l2.s.y,l2.e.y) && 59 max(l2.s.y,l2.e.y) >= min(l1.s.y,l1.e.y) && 60 sgn((l2.s-l1.e)^(l1.s-l1.e))*sgn((l2.e-l1.e)^(l1.s-l1.e)) <= 0 && 61 sgn((l1.s-l2.e)^(l2.s-l2.e))*sgn((l1.e-l2.e)^(l2.s-l2.e)) <= 0; 62 } 63 64 struct Node 65 { 66 char id; 67 int n;//点数 68 Point p[22]; 69 }node[30]; 70 bool cmp(Node a,Node b) 71 { 72 return a.id < b.id; 73 } 74 char str[30]; 75 bool check(Node a,Node b) 76 { 77 for(int i = 0;i < a.n;i++) 78 for(int j = 0;j < b.n;j++) 79 if(inter(Line(a.p[i],a.p[(i+1)%a.n]),Line(b.p[j],b.p[(j+1)%b.n]))) 80 return true; 81 return false; 82 } 83 bool ff[30]; 84 int main() 85 { 86 //freopen("in.txt","r",stdin); 87 //freopen("out.txt","w",stdout); 88 int n; 89 while(scanf("%s",str) == 1) 90 { 91 if(str[0] == ‘.‘)break; 92 node[0].id = str[0]; 93 scanf("%s",str); 94 if(strcmp(str,"square")==0) 95 { 96 node[0].n = 4; 97 scanf(" (%lf,%lf)",&node[0].p[0].x,&node[0].p[0].y); 98 //cout<<node[0].p[0].x<<" "<<node[0].p[0].y<<endl; 99 scanf(" (%lf,%lf)",&node[0].p[2].x,&node[0].p[2].y); 100 // cout<<node[0].p[2].x<<" "<<node[0].p[2].y<<endl; 101 node[0].p[1].x = ((node[0].p[0].x+node[0].p[2].x)+(node[0].p[2].y-node[0].p[0].y))/2; 102 node[0].p[1].y = ((node[0].p[0].y+node[0].p[2].y)+(node[0].p[0].x-node[0].p[2].x))/2; 103 node[0].p[3].x = ((node[0].p[0].x+node[0].p[2].x)-(node[0].p[2].y-node[0].p[0].y))/2; 104 node[0].p[3].y = ((node[0].p[0].y+node[0].p[2].y)-(node[0].p[0].x-node[0].p[2].x))/2; 105 } 106 else if(strcmp(str,"line")==0) 107 { 108 node[0].n = 2; 109 scanf(" (%lf,%lf)",&node[0].p[0].x,&node[0].p[0].y); 110 scanf(" (%lf,%lf)",&node[0].p[1].x,&node[0].p[1].y); 111 } 112 else if(strcmp(str,"triangle")==0) 113 { 114 node[0].n = 3; 115 scanf(" (%lf,%lf)",&node[0].p[0].x,&node[0].p[0].y); 116 scanf(" (%lf,%lf)",&node[0].p[1].x,&node[0].p[1].y); 117 scanf(" (%lf,%lf)",&node[0].p[2].x,&node[0].p[2].y); 118 } 119 else if(strcmp(str,"rectangle")==0) 120 { 121 node[0].n = 4; 122 scanf(" (%lf,%lf)",&node[0].p[0].x,&node[0].p[0].y); 123 scanf(" (%lf,%lf)",&node[0].p[1].x,&node[0].p[1].y); 124 scanf(" (%lf,%lf)",&node[0].p[2].x,&node[0].p[2].y); 125 node[0].p[3].x = node[0].p[2].x + (node[0].p[0].x - node[0].p[1].x); 126 node[0].p[3].y = node[0].p[2].y + (node[0].p[0].y - node[0].p[1].y); 127 } 128 else if(strcmp(str,"polygon")==0) 129 { 130 scanf("%d",&node[0].n); 131 for(int i = 0;i < node[0].n;i++) 132 { 133 scanf(" (%lf,%lf)",&node[0].p[i].x,&node[0].p[i].y); 134 } 135 } 136 n = 1; 137 while(scanf("%s",str)==1) 138 { 139 140 //cout<<str<<endl; 141 if(str[0] == ‘-‘)break; 142 node[n].id = str[0]; 143 scanf("%s",str); 144 if(strcmp(str,"square")==0) 145 { 146 node[n].n = 4; 147 scanf(" (%lf,%lf)",&node[n].p[0].x,&node[n].p[0].y); 148 scanf(" (%lf,%lf)",&node[n].p[2].x,&node[n].p[2].y); 149 node[n].p[1].x = ((node[n].p[0].x+node[n].p[2].x)+(node[n].p[2].y-node[n].p[0].y))/2; 150 node[n].p[1].y = ((node[n].p[0].y+node[n].p[2].y)+(node[n].p[0].x-node[n].p[2].x))/2; 151 node[n].p[3].x = ((node[n].p[0].x+node[n].p[2].x)-(node[n].p[2].y-node[n].p[0].y))/2; 152 node[n].p[3].y = ((node[n].p[0].y+node[n].p[2].y)-(node[n].p[0].x-node[n].p[2].x))/2; 153 } 154 else if(strcmp(str,"line")==0) 155 { 156 node[n].n = 2; 157 scanf(" (%lf,%lf)",&node[n].p[0].x,&node[n].p[0].y); 158 scanf(" (%lf,%lf)",&node[n].p[1].x,&node[n].p[1].y); 159 } 160 else if(strcmp(str,"triangle")==0) 161 { 162 node[n].n = 3; 163 scanf(" (%lf,%lf)",&node[n].p[0].x,&node[n].p[0].y); 164 scanf(" (%lf,%lf)",&node[n].p[1].x,&node[n].p[1].y); 165 scanf(" (%lf,%lf)",&node[n].p[2].x,&node[n].p[2].y); 166 } 167 else if(strcmp(str,"rectangle")==0) 168 { 169 node[n].n = 4; 170 scanf(" (%lf,%lf)",&node[n].p[0].x,&node[n].p[0].y); 171 scanf(" (%lf,%lf)",&node[n].p[1].x,&node[n].p[1].y); 172 scanf(" (%lf,%lf)",&node[n].p[2].x,&node[n].p[2].y); 173 node[n].p[3].x = node[n].p[2].x + (node[n].p[0].x - node[n].p[1].x); 174 node[n].p[3].y = node[n].p[2].y + (node[n].p[0].y - node[n].p[1].y); 175 } 176 else if(strcmp(str,"polygon")==0) 177 { 178 scanf("%d",&node[n].n); 179 for(int i = 0;i < node[n].n;i++) 180 { 181 scanf(" (%lf,%lf)",&node[n].p[i].x,&node[n].p[i].y); 182 } 183 } 184 n++; 185 } 186 sort(node,node+n,cmp); 187 for(int i = 0;i < n;i++) 188 { 189 printf("%c ",node[i].id); 190 memset(ff,false,sizeof(ff)); 191 int cnt = 0; 192 for(int j = 0;j < n;j++) 193 if(i != j) 194 if(check(node[i],node[j])) 195 { 196 cnt++; 197 ff[j] = true; 198 } 199 if(cnt == 0)printf("has no intersections\n"); 200 else if(cnt == 1) 201 { 202 printf("intersects with "); 203 for(int j = 0 ; j < n;j++) 204 if(ff[j]) 205 { 206 printf("%c\n",node[j].id); 207 break; 208 } 209 } 210 else if(cnt == 2) 211 { 212 printf("intersects with "); 213 for(int j = 0 ; j < n;j++) 214 if(ff[j]) 215 { 216 if(cnt==2)printf("%c ",node[j].id); 217 if(cnt==1)printf("and %c\n",node[j].id); 218 cnt--; 219 } 220 } 221 else 222 { 223 printf("intersects with "); 224 for(int j = 0 ; j < n;j++) 225 if(ff[j]) 226 { 227 if(cnt > 1)printf("%c, ",node[j].id); 228 if(cnt==1)printf("and %c\n",node[j].id); 229 cnt--; 230 } 231 } 232 } 233 234 printf("\n"); 235 } 236 }
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