poj 1151-atlantis-线段树扫描线求面积并

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <algorithm>
  4 #include <vector>
  5 using namespace std;
  6 #define maxn 300
  7 #define lson l, m, rt<<1
  8 #define rson m+1, r, rt<<1|1
  9 struct st
 10 {
 11     int cover;
 12     double len;
 13 };
 14 vector<st> sgt;
 15 int n;
 16 struct Line
 17 {
 18     double x, y_up, y_down;
 19     int sign;
 20     bool operator < (const Line that) const {
 21         return x < that.x;
 22     }
 23 };
 24 vector<Line> line;
 25 vector<double> Y;
 26 void input()
 27 {
 28     line.clear();
 29     Y.clear();
 30     sgt.clear();
 31     sgt.resize(maxn<<1);
 32     double x, y, a, b;
 33     Line read;
 34     scanf("%lf%lf%lf%lf", &x, &y, &a, &b);
 35     read.x = x; read.sign = 1; read.y_down = y; read.y_up = b;
 36     line.push_back(read); Y.push_back(y);
 37     read.x = a; read.sign = -1;
 38     line.push_back(read); Y.push_back(b);
 39     for(int i = 1; i < n; i++) {
 40         scanf("%lf%lf%lf%lf", &x, &y, &a, &b);
 41         read.x = x; read.sign = 1; read.y_down = y; read.y_up = b;
 42         line.push_back(read);
 43         read.x = a; read.sign = -1;
 44         line.push_back(read);
 45         bool flag1 = 0, flag2 = 0; int l = Y.size();
 46         for(int j = 0; j < l; j++) {
 47             if(Y[j] == y) flag1 = 0;
 48             if(Y[j] == b) flag2 = 0;
 49          }
 50          if(!flag1) Y.push_back(y);
 51          if(!flag2) Y.push_back(b);
 52     }
 53     sort(line.begin(), line.end());
 54     sort(Y.begin(), Y.end());
 55 }
 56 
 57 void build(int l, int r, int rt)
 58 {
 59     sgt[rt].cover = 0;
 60     sgt[rt].len = 0;
 61     if(l == r) {
 62         sgt[rt].len = Y[l] - Y[l-1];
 63         return;
 64     }
 65     int m = (l + r)>>1;
 66     build(lson);
 67     build(rson);
 68 }
 69 void insert(int l, int r, int rt, int L, int R, int sign)
 70 {
 71     if(l == r) {
 72         sgt[rt].cover += sign;
 73         return;
 74     }
 75     sgt[rt].len = 0;
 76     int m = (l+r)>>1;
 77     if(L <= m)  insert(lson, L, R, sign);
 78     if(m < R)  insert(rson, L, R, sign);
 79 }
 80 double getSum(int l, int r, int rt)
 81 {
 82     if(l == r) {
 83         if(sgt[rt].cover > 0) return sgt[rt].len;
 84         return 0;
 85     }
 86     int m = (l + r)>>1;
 87     double a, b, ans;
 88     ans = getSum(lson);
 89     ans += getSum(rson);
 90     return ans;
 91 }
 92 struct node
 93 {
 94     int st, nd;
 95 };
 96 node getNum(double y1, double y2)
 97 {
 98     int l = Y.size();
 99     node res;
100     for(int i = 0; i < l; i++) {
101         if(Y[i] == y1) res.st = i+1;
102         if(Y[i] == y2) res.nd = i;
103     }
104     return res;
105 }
106 void work(int cas)
107 {
108     input();
109     int N = Y.size();
110     build(1, N-1, 1);
111     int l = line.size();
112     double ans = 0;
113     for(int i = 0; i < l; i++) {
114         node rec = getNum(line[i].y_down, line[i].y_up);
115         if(i == 0) insert(1, N-1, 1, rec.st, rec.nd, line[i].sign );
116         if(i == 0) continue;
117         double length = line[i].x - line[i-1].x;
118         ans += length*getSum(1, N-1, 1);
119         insert(1, N-1, 1, rec.st, rec.nd, line[i].sign );
120     }
121     printf("Test case #%d\nTotal explored area: %0.2f\n\n", cas, ans);
122 }
123 int main()
124 {
125     int cnt = 0;
126     while(1) {
127         scanf("%d", &n); if(n == 0) break;
128         work(++cnt);
129     }
130     return 0;
131 }