【HDOJ】1542 Atlantis

离散化+线段树+扫描线，求覆盖面积。

  1 /* 1542 */
  2 #include <iostream>
  3 #include <string>
  4 #include <map>
  5 #include <queue>
  6 #include <set>
  7 #include <stack>
  8 #include <vector>
  9 #include <deque>
 10 #include <algorithm>
 11 #include <cstdio>
 12 #include <cmath>
 13 #include <ctime>
 14 #include <cstring>
 15 #include <climits>
 16 #include <cctype>
 17 #include <cassert>
 18 #include <functional>
 19 #include <iterator>
 20 #include <iomanip>
 21 using namespace std;
 22 //#pragma comment(linker,"/STACK:102400000,1024000")
 23
 24 #define sti                set<int>
 25 #define stpii            set<pair<int, int> >
 26 #define mpii            map<int,int>
 27 #define vi                vector<int>
 28 #define pii                pair<int,int>
 29 #define vpii            vector<pair<int,int> >
 30 #define rep(i, a, n)     for (int i=a;i<n;++i)
 31 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 32 #define clr                clear
 33 #define pb                 push_back
 34 #define mp                 make_pair
 35 #define fir                first
 36 #define sec                second
 37 #define all(x)             (x).begin(),(x).end()
 38 #define SZ(x)             ((int)(x).size())
 39 #define lson            l, mid, rt<<1
 40 #define rson            mid+1, r, rt<<1|1
 41
 42 typedef struct segment_t {
 43     double l, r, h;
 44     int f;
 45
 46     friend bool operator< (const segment_t& a, const segment_t& b) {
 47         return a.h < b.h;
 48     }
 49
 50 } segment_t;
 51
 52 typedef struct {
 53     int l, r, c;
 54     double len;
 55 } node_t;
 56
 57 const int maxn = 205;
 58 double X[maxn];
 59 segment_t seg[maxn];
 60 node_t nd[maxn<<2];
 61
 62 void build(int l, int r, int rt) {
 63     nd[rt].l = l;
 64     nd[rt].r = r;
 65     nd[rt].c = 0;
 66     nd[rt].len = 0;
 67
 68     if (l == r)
 69         return ;
 70
 71     int mid = (l + r) >> 1;
 72     build(lson);
 73     build(rson);
 74 }
 75
 76 void PushUp(int rt) {
 77     if (nd[rt].c)
 78         nd[rt].len = X[nd[rt].r+1] - X[nd[rt].l];
 79     else if (nd[rt].r == nd[rt].l)
 80         nd[rt].len = 0;
 81     else
 82         nd[rt].len = nd[rt<<1].len + nd[rt<<1|1].len;
 83 }
 84
 85 void update(int L, int R, int delta, int rt) {
 86     if (L<=nd[rt].l && nd[rt].r<=R) {
 87         nd[rt].c += delta;
 88         PushUp(rt);
 89         return ;
 90     }
 91
 92     int mid = (nd[rt].l + nd[rt].r) >> 1;
 93
 94     if (mid >= R) {
 95         update(L, R, delta, rt<<1);
 96     } else if (mid < L) {
 97         update(L, R, delta, rt<<1|1);
 98     } else {
 99         update(L, R, delta, rt<<1);
100         update(L, R, delta, rt<<1|1);
101     }
102
103     PushUp(rt);
104 }
105
106 int main() {
107     ios::sync_with_stdio(false);
108     #ifndef ONLINE_JUDGE
109         freopen("data.in", "r", stdin);
110         freopen("data.out", "w", stdout);
111     #endif
112
113     int n, m, xn;
114     double x1, x2, y1, y2;
115     double ans;
116     int L, R;
117     int tt = 0;
118
119     while (scanf("%d",&n)!=EOF && n) {
120         ans = 0.;
121         m = 0;
122         rep(i, 0, n) {
123             scanf("%lf %lf %lf %lf", &x1,&y1,&x2,&y2);
124             seg[m].l = seg[m+1].l = x1;
125             seg[m].r = seg[m+1].r = x2;
126             seg[m].h = y1;
127             seg[m].f = 1;
128             seg[m+1].h = y2;
129             seg[m+1].f = -1;
130
131             X[m] = x1;
132             X[m+1] = x2;
133
134             m += 2;
135         }
136
137         sort(seg, seg+m);
138         sort(X, X+m);
139         xn = unique(X, X+m)-X;
140
141         build(0, xn-1, 1);
142
143         rep(i, 0, m) {
144             L = lower_bound(X, X+xn, seg[i].l) - X;
145             R = lower_bound(X, X+xn, seg[i].r) - X - 1;
146             update(L, R, seg[i].f, 1);
147             ans += (seg[i+1].h - seg[i].h) * nd[1].len;
148             #ifndef ONLINE_JUDGE
149                 printf("L = %d, R = %d, len = %.2lf\n", L, R, nd[1].len);
150             #endif
151         }
152
153         printf("Test case #%d\n", ++tt);
154         printf("Total explored area: %.02lf\n\n", ans);
155     }
156
157     #ifndef ONLINE_JUDGE
158         printf("time = %d.\n", (int)clock());
159     #endif
160
161     return 0;
162 }