HDU-1542 Atlantis 【线段树+扫描线】

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<algorithm>
  4 #include<cstring>
  5 using namespace std;
  6 #define INF 0x3f3f3f3f
  7 #define M(a, b) memset(a, b, sizeof(a))
  8 #define lson o<<1
  9 #define rson o<<1|1
 10 const int N = 200 + 5;
 11 int cnt[N<<2], qL, qR, v;
 12 double X[N], sum[N<<2];
 13 struct Segment {
 14     double l, r, h;
 15     int f;
 16     Segment() {}
 17     Segment(double l, double r, double h, int f): l(l), r(r), h(h), f(f) {} 
 18     bool operator < (const Segment &rhs) const {
 19         return h < rhs.h;
 20     }
 21 }node[N];
 22 
 23 void pushdown(int o, int L, int R) {
 24     if (~cnt[o]) {
 25         int M = (L + R) >> 1;
 26         cnt[lson] = cnt[rson] = cnt[o];
 27         sum[lson] = cnt[lson] ? X[M+1]-X[L] : 0;
 28         sum[rson] = cnt[rson] ? X[R+1]-X[M+1] : 0;
 29     }
 30 }  
 31 
 32 void pushup(int o, int L, int R) {
 33     if (~cnt[lson] || ~cnt[rson]) cnt[o] = -1;
 34     else if (cnt[lson] != cnt[rson]) cnt[o] = -1;
 35     else {
 36         cnt[o] = cnt[lson];
 37     }
 38     sum[o] = sum[lson] + sum[rson];
 39 }
 40 
 41 void build(int o, int L, int R) {
 42     if (L == R) {cnt[o] = 0; sum[o] = 0;}
 43     else {
 44         int M = (L + R) >> 1;
 45         build(lson, L, M);
 46         build(rson, M+1, R);
 47         pushup(o, L, R);
 48     }
 49 }
 50 
 51 void update(int o, int L, int R) {
 52     if (qL <= L && R <= qR) {
 53         if (~cnt[o]) {
 54             cnt[o] += v;
 55             sum[o] = cnt[o] ? X[R+1]-X[L] : 0;
 56             return;
 57         }
 58     }
 59     int M = (L + R) >> 1;
 60     pushdown(o, L, R);
 61     if (qL <= M) update(lson, L, M);
 62     if (M < qR) update(rson, M+1, R);
 63     pushup(o, L, R);
 64 }
 65 
 66 int bin(int L, int R, double key) {
 67     while (L < R) {
 68         int M = (L + R) >> 1;
 69         if (X[M] == key) return M;
 70         else if (X[M] < key) L = M + 1;
 71         else R = M - 1; 
 72     }
 73     return L;
 74 }
 75 
 76 int main() {
 77     int T = 0, n;
 78     while (scanf("%d", &n), n) {
 79         double x1, x2, y1, y2;
 80         int num = 0, nn = 0;
 81         for (int i = 1; i <= n; ++i) {
 82             scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
 83             X[++num] = x1; X[++num] = x2;
 84             node[++nn] = Segment(x1, x2, y1, 1);
 85             node[++nn] = Segment(x1, x2, y2, -1);
 86         }
 87         sort(X+1, X+1+num); sort(node+1, node+1+nn);
 88         int k = 1;
 89         for (int i = 2; i <= nn; ++i)
 90             if (X[i] != X[i-1]) X[++k] = X[i];
 91         build(1, 1, k-1);
 92         double ans = 0;
 93         for (int i = 1; i < nn; ++i) {
 94             qL = bin(1, k, node[i].l);
 95             qR = bin(1, k, node[i].r)-1;
 96             v = node[i].f;
 97             if(qL <= qR) update(1, 1, k-1);
 98             ans += sum[1] * (node[i+1].h-node[i].h);
 99         }
100         printf("Test case #%d\n", ++T);
101         printf("Total explored area: %.2f\n\n", ans);
102     }
103 
104     return 0;
105 }