学步园

http://acm.hdu.edu.cn/showproblem.php?pid=1542

单纯的线段树+扫描线求面积并，需要离散化。

code:

#include <cstdlib>
#include <cctype>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <set>
#include <queue>
#include <stack>
#include <fstream>
#include <iomanip>
#include <bitset>
#include <list>
#include <ctime>
using namespace std ;
#define SET(arr, what)  memset(arr, what, sizeof(arr))
#define FF(i, a)        for(i=0; i<a; i++)
#define SD(a)           scanf("%d", &a)
#define SSD(a, b)       scanf("%d%d", &a, &b)
#define SSF(a, b)       scanf("%lf%lf", &a, &b)
#define SS(a)           scanf("%s", a)
#define SLD(a)          scanf("%lld", &a)
#define PF(a)           printf("%d\n", a)
#define PPF(a, b)       printf("%d %d\n", a, b)
#define PLF(a)          printf("%lf\n", a)
#define SZ(arr)         (int)a.size()
#define SWAP(a,b)       a=a xor b;b= a xor b;a=a xor b;
#define read            freopen("in.txt", "r", stdin)
#define write            freopen("out.txt", "w", stdout)
#define MAX             1<<30
#define ESP             1e-5
#define lson            l, m, rt<<1
#define rson            m+1, r, rt<<1|1
template<class T> inline T sqr(T a){return a*a;}
template<class T> inline void AMin(T &a,T b){if(a==-1||a>b)a=b;}
template<class T> inline void AMax(T &a,T b){if(a<b)a=b;}
template<class T> inline T Min(T a,T b){return a>b?b:a;}
template<class T> inline T Max(T a,T b){return a>b?a:b;}
const int maxn = 2222 ;
int cover[maxn<<2] ;
double sum[maxn<<2], s[maxn] ;
struct Seg{
    double l, r, h ;
    int d ;
}seg[maxn] ;
int cmp1(const void *a, const void *b){
    return (*(Seg *)a).h < (*(Seg *)b).h ? -1 : 1 ;
}
int cmp2(const void *a, const void *b){
    return *(double *)a < *(double *)b ? -1 : 1 ;
}
void setSeg(double l, double r, int d, double h, int cnt){
    seg[cnt].l = l ;
    seg[cnt].r = r ;
    seg[cnt].d = d ;
    seg[cnt].h = h ;
}
void pushup(int rt, int l, int r){
    if(cover[rt])   sum[rt] = s[r+1] - s[l] ;
    else if(l==r)   sum[rt] = 0 ;
    else            sum[rt] = sum[rt<<1] + sum[rt<<1|1] ;
}
int find(double val, int r){
    int l = 0 ;
    while(l<=r){
        int m = (l + r) >> 1 ;
        if(val==s[m])   return m ;
        if(val>s[m]) l = m + 1 ;
        else    r = m - 1 ;
    }
    return -1 ;
}
void update(int L, int R, int d, int l, int r, int rt){
    if(L<=l&&r<=R){
        cover[rt] += d ;
        pushup(rt, l, r) ;
        return ;
    }
    int m = (l + r) >> 1 ;
    if(L<=m)    update(L, R, d, lson) ;
    if(R>m)     update(L, R, d, rson) ;
    pushup(rt, l, r) ;
}
int main(){
    int n, t=1, i, x, y, j, m ;
    double a, b, c, d, ans ;
    while(~SD(n)&&n){
        x = y = 0 ;
        FF(i, n){
            SSF(a, b) ;SSF(c, d) ;
            s[y++] = a ;
            s[y++] = c ;
            setSeg(a, c, 1, b, x++) ;
            setSeg(a, c, -1, d, x++) ;
        }
        qsort(seg, x, sizeof(Seg), cmp1) ;
        qsort(s, x, sizeof(double), cmp2) ;
        m = 1 ;
        for(i=1; i<y; i++)  if(s[i]!=s[i-1])    s[m++] = s[i] ;
        SET(sum, 0) ;
        SET(cover, 0) ;
        ans = 0 ;
        FF(i, x-1){
            int l = find(seg[i].l, m-1) ;
            int r = find(seg[i].r, m-1) - 1 ;
            if(l<=r)    update(l, r, seg[i].d, 0, m-1, 1) ;
            ans += sum[1] * (seg[i+1].h - seg[i].h) ;
        }
        printf("Test case #%d\n", t++) ;
        printf("Total explored area: %.2lf\n\n", ans) ;
    }
    return 0 ;
}