POJ 1151Atlantis 扫描线+线段树求矩形面积并

题目链接

 #include <iostream>
 #include <vector>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <cmath>
 #include <map>
 #include <set>
 #include <string>
 #include <queue>
 #include <stack>
 #include <bitset>
 using namespace std;
 #define pb(x) push_back(x)
 #define ll long long
 #define mk(x, y) make_pair(x, y)
 #define lson l, m, rt<<1
 #define mem(a) memset(a, 0, sizeof(a))
 #define rson m+1, r, rt<<1|1
 #define mem1(a) memset(a, -1, sizeof(a))
 #define mem2(a) memset(a, 0x3f, sizeof(a))
 #define rep(i, n, a) for(int i = a; i<n; i++)
 #define fi first
 #define se second
 typedef pair<int, int> pll;
 const double PI = acos(-1.0);
 const double eps = 1e-;
 const int mod = 1e9+;
 const int inf = ;
 const int dir[][] = { {-, }, {, }, {, -}, {, } };
 const int maxn = ;
 struct segment
 {
     double l, r, h;
     int flag;
     segment(){}
     segment(double l, double r, double h, int flag):l(l), r(r), h(h), flag(flag){}
     bool operator < (segment a) const
     {
         return h<a.h;
     }
 }line[maxn];
 double a[maxn], sum[maxn<<];
 int cover[maxn<<];
 void pushUp(int rt, int l, int r) {
     if(cover[rt]) {
         sum[rt] = a[r+]-a[l];
     } else if(l == r) {
         sum[rt] = ;
     } else {
         sum[rt] = sum[rt<<]+sum[rt<<|];
     }
 }
 void update(int L, int R, int l, int r, int rt, int flag) {
     if(L<=l&&R>=r) {
         cover[rt] += flag;
         pushUp(rt, l-, r-);
         return ;
     }
     int m = l+r>>;
     if(L<=m)
         update(L, R, lson, flag);
     if(R>m)
         update(L, R, rson, flag);
     pushUp(rt, l-, r-);
 }
 int main()
 {
     int n, cnt, k = ;
     double x1, y1, x2, y2;
     while(scanf("%d", &n)&&n) {
         cnt = ;
         mem(cover);
         for(int i = ; i<n; i++) {
             scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
             line[cnt] = segment(x1, x2, y1, );
             a[cnt++] = x1;
             line[cnt] = segment(x1, x2, y2, -);
             a[cnt++] = x2;
         }
         sort(a, a+cnt);
         sort(line, line+cnt);
         double ans = ;
         int num = unique(a, a+cnt)-a;
         for(int i = ; i<cnt; i++) {
             int L = lower_bound(a, a+num, line[i].l)-a+;
             int R = lower_bound(a, a+num, line[i].r)-a;
             update(L, R, , num, , line[i].flag);
             ans += sum[]*(line[i+].h-line[i].h);
         }
         printf("Test case #%d\n", k++);
         printf("Total explored area: %.2f\n\n", ans);
     }
     return ;
 }