矩形的并(算法)

#include <stdio.h>
#include <set>
using namespace std;
typedef struct ls      
{  
     double l, r;    
     double y;       
     int UpOrDown;  
}ls;  

int par(ls L[], int low, int high) {
    L[0] = L[low];
    double pivotkey = L[low].y;
    while(low < high) {
        while(low < high && L[high].y <= pivotkey)  --high;
        L[low] = L[high];
        while(low < high && L[low].y >= pivotkey) ++low;
        L[high] = L[low];
    }
    L[low] = L[0];
    return low;
}
void qsort(ls L[], int low, int high) {
    if(low < high) {
        double pivotloc = par(L, low, high);
        qsort(L, low, pivotloc - 1);
        qsort(L, pivotloc + 1, high);
    }
}