HDU 1542

每次添加，计算出被覆盖的长度，离散化X坐标，按Y坐标排序加入即可。

今天好伤心，我好水。。。。

#include <cstdio>  
#include <cstring>  
#include <cctype>  
#include <algorithm>  
using namespace std;  
#define lson l , m , rt << 1  
#define rson m + 1 , r , rt << 1 | 1  
   
const int maxn = 2222;  
int cnt[maxn << 2];  
double sum[maxn << 2];  
double X[maxn];  
struct Seg {  
    double h , l , r;  
    int s;  
    Seg(){}  
    Seg(double a,double b,double c,int d) : l(a) , r(b) , h(c) , s(d) {}  
    bool operator < (const Seg &cmp) const {  
        return h < cmp.h;  
    }  
}ss[maxn];  
void PushUp(int rt,int l,int r) {  
    if (cnt[rt]) sum[rt] = X[r+1] - X[l];  
    else if (l == r) sum[rt] = 0;  
    else sum[rt] = sum[rt<<1] + sum[rt<<1|1];  
}  
void update(int L,int R,int c,int l,int r,int rt) {  
    if (L <= l && r <= R) {  
        cnt[rt] += c;  
        PushUp(rt , l , r);  
        return ;  
    }  
    int m = (l + r) >> 1;  
    if (L <= m) update(L , R , c , lson);  
    if (m < R) update(L , R , c , rson);  
    PushUp(rt , l , r);  
}  
int Bin(double key,int n,double X[]) {  
    int l = 0 , r = n - 1;  
    while (l <= r) {  
        int m = (l + r) >> 1;  
        if (X[m] == key) return m;  
        if (X[m] < key) l = m + 1;  
        else r = m - 1;  
    }  
    return -1;  
}  
int main() {  
    int n , cas = 1;  
    while (~scanf("%d",&n) && n) {  
        int m = 0;  
        while (n --) {  
            double a , b , c , d;  
            scanf("%lf%lf%lf%lf",&a,&b,&c,&d);  
            X[m] = a;  
            ss[m++] = Seg(a , c , b , 1);  
            X[m] = c;  
            ss[m++] = Seg(a , c , d , -1);  
        }  
        sort(X , X + m);  
        sort(ss , ss + m);  
        int k = 1;  
        for (int i = 1 ; i < m ; i ++) {  
            if (X[i] != X[i-1]) X[k++] = X[i];  
        }  
        memset(cnt , 0 , sizeof(cnt));  
        memset(sum , 0 , sizeof(sum));  
        double ret = 0;  
        for (int i = 0 ; i < m - 1 ; i ++) {  
            int l = Bin(ss[i].l , k , X);  
            int r = Bin(ss[i].r , k , X) - 1;  
            if (l <= r) update(l , r , ss[i].s , 0 , k - 1, 1);  
            ret += sum[1] * (ss[i+1].h - ss[i].h);  
        }  
        printf("Test case #%d
Total explored area: %.2lf

",cas++ , ret);  
    }  
    return 0;  
}