Atlantis POJ 1151 HDU 1542

タイトルリンク:POJ HDU

    There are several ancient Greek texts that contain descriptions of the fabled island Atlantis. Some of these texts even include maps of parts of the island. But unfortunately, these maps describe different regions of Atlantis. Your friend Bill has to know the total area for which maps exist. You (unwisely) volunteered to write a program that calculates this quantity. 

Input

    The input file consists of several test cases. Each test case starts with a line containing a single integer n (1<=n<=100) of available maps. The n following lines describe one map each. Each of these lines contains four numbers x1;y1;x2;y2 (0<=x1

Output

    For each test case, your program should output one section. The first line of each section must be “Test case #k”, where k is the number of the test case (starting with 1). The second one must be “Total explored area: a”, where a is the total explored area (i.e. the area of the union of all rectangles in this test case), printed exact to two digits to the right of the decimal point. 

    Output a blank line after each test case. 

Sample Input

2
10 10 20 20
15 15 25 25.5
0

Sample Output

Test case #1
Total explored area: 180.00 

タイトル:

  n      ,    n             .

考え方:

          ,                ,               ,            

コード:

#include
#include
#include
#include
#include
using namespace std;

#define lson cur<<1,l,mid
#define rson cur<<1|1,mid+1,r
const int maxn = 4500;

struct ss{
    double lx,rx,y;
    int tag;//      1 -1,          
    ss(){};
    ss (double xx,double xy,double xk, int t){
    lx = xx;rx = xy;y = xk;tag = t;};
    bool operator const ss &q)const{
    return y < q.y;
    }
}a[maxn];
double x[maxn];
double sum[maxn];
int flag[maxn];//    

void pushup(int cur, int l, int r){
    if(flag[cur]) sum[cur] = x[r+1] - x[l];//        
    else if(l ==r) sum[cur] = 0;
    else sum[cur] = sum[cur<<1] + sum[cur<<1|1];
}

void update(int cur, int l,int r, int ll,int rr,int v){
    if(ll <= l && rr>= r){
        flag[cur] += v;
        pushup(cur,l,r);
        return ;
    }
    int mid = (l + r)>> 1;
    if (mid >= ll) update(lson,ll,rr,v);
    if (mid < rr) update(rson,ll,rr,v);
    pushup(cur,l,r);
}

int main(){
    int n;
    int kase = 0;
    while(scanf("%d", &n) ,n){
        int num = 0;
        memset(flag,0,sizeof(flag));
        memset(sum,0,sizeof(sum));
        for(int i = 1; i <= n;++i){
            double a1,a2,b1,b2;
            scanf("%lf %lf %lf %lf", &a1, &b1, &a2, &b2);
            a[++num] = ss(a1,a2,b1,1);
            x[num] = a1;//   x   
            a[++num] = ss(a1,a2,b2,-1);
            x[num] = a2;
        }sort(x+1,x+1+num);//  
        sort(a+1,a+1+num);
        int k = 1;double ans = 0;
        for(int i = 2; i<= num; ++i)
            if(x[i] != x[i+1])
                x[++k] = x[i];//  
        for(int i = 1; i < num; ++i){
            int l = lower_bound(x+1,x+1+k,a[i].lx) - x;//  x        
            int r = lower_bound(x+1,x+1+k,a[i].rx) - x - 1;
            update(1,1,k,l,r,a[i].tag);
            ans += sum[1] * (a[i+1].y - a[i].y);
        }printf("Test case #%d
", ++kase);
        printf("Total explored area: %.2f

",ans);
    }return 0;
}