Poj--3788（判点在多边形内）

2014-12-07 01:10:39

思路：由于这题保证多边形凸，呼呼，偷懒下用三角面积和等于多边形来判断...具体做法？！，枚举点即可 hhhh

  1 /*************************************************************************
  2     > File Name: 3788.cpp
  3     > Author: Nature
  4     > Mail: 564374850@qq.com 
  5     > Created Time: Sat 06 Dec 2014 01:18:19 PM CST
  6 ************************************************************************/
  7 
  8 #include <cstdio>
  9 #include <cstring>
 10 #include <cstdlib>
 11 #include <cmath>
 12 #include <vector>
 13 #include <map>
 14 #include <set>
 15 #include <stack>
 16 #include <queue>
 17 #include <iostream>
 18 #include <algorithm>
 19 using namespace std;
 20 #define lp (p << 1)
 21 #define rp (p << 1|1)
 22 #define getmid(l,r) (l + (r - l) / 2)
 23 #define MP(a,b) make_pair(a,b)
 24 typedef long long ll;
 25 const int INF = 1 << 30;
 26 const double eps = 1e-6;
 27 
 28 int T,tag,n,xmin,xmax,ymin,ymax;
 29 double d[60],starea;
 30 int ans[100000][3],cnt;
 31 
 32 struct point{
 33     int x,y;
 34 }p[60];
 35 
 36 double Cal_dis(point a,point b){
 37     return sqrt(1.0 * (a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
 38 }
 39 
 40 double Cal_area(point st,point a,point b){
 41     int x1 = a.x - st.x;
 42     int y1 = a.y - st.y;
 43     int x2 = b.x - st.x;
 44     int y2 = b.y - st.y;
 45     return fabs(1.0 * x1 * y2 - x2 * y1) * 0.5;
 46 }
 47 
 48 bool Judge(int x,int y){
 49     double area = 0.0;
 50     point t;
 51     t.x = x;
 52     t.y = y;
 53     for(int i = 1; i <= n; ++i){
 54         double tmp;
 55         if(i == n) tmp = Cal_area(t,p[n],p[1]);
 56         else tmp = Cal_area(t,p[i],p[i + 1]);
 57         if(tmp < eps)
 58             return false;
 59         area += tmp;
 60     }
 61     if(fabs(area - starea) < eps)
 62         return true;
 63     return false;
 64 }
 65 
 66 int main(){
 67     scanf("%d",&T);
 68     while(T--){
 69         cnt = 0;
 70         starea = 0.0;
 71         xmax = ymax = -INF;
 72         xmin = ymin = INF;
 73         scanf("%d%d",&tag,&n);
 74         for(int i = 1; i <= n; ++i){
 75             scanf("%d%d",&p[i].x,&p[i].y);
 76             xmax = max(xmax,p[i].x);
 77             xmin = min(xmin,p[i].x);
 78             ymin = min(ymin,p[i].y);
 79         }
 80         ymax = p[1].y;
 81         for(int i = 2; i < n; ++i){
 82             starea += Cal_area(p[1],p[i],p[i + 1]);
 83         }
 84         for(int j = ymax; j >= ymin; --j){
 85             int i,l = -1,r = -1;
 86             for(i = xmin; i <= xmax; ++i){
 87                 if(Judge(i,j)){
 88                     if(l == -1) l = i;
 89                     r = i;
 90                 }
 91             }
 92             if(l != -1){
 93                 ans[++cnt][0] = j;
 94                 ans[cnt][1] = l;
 95                 ans[cnt][2] = r;
 96             }
 97         }
 98         printf("%d %d\n",tag,cnt);
 99         for(int i = 1; i <= cnt; ++i){
100             printf("%d %d %d\n",ans[i][0],ans[i][1],ans[i][2]);
101         }
102     }
103     return 0;
104 }

 

posted @ 2014-12-07 01:11  Naturain  阅读(154)  评论(0)  编辑  收藏  举报