sdut 2401 最大矩阵面积

http://acm.sdut.edu.cn/sdutoj/problem.php?action=showproblem&problemid=2401

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

const int N=1010;
struct node
{
    int x,y;
}mem[N];
bool cmp(node a,node b)
{
    if(a.x==b.x)
    return a.y<b.y;
    return a.x<b.x;
}
bool cmp1(node a,node b)
{
    if(a.y==b.y)
    return a.x<b.x;
    return a.y<b.y;
}
int main()
{
    //freopen("data.txt","r",stdin);
    int T;
    int L,W,Point;
    cin>>T;
    while(T--)
    {
        cin>>L>>W;
        mem[0].x=0;mem[0].y=0;
        mem[1].x=0;mem[1].y=W;
        mem[2].x=L;mem[2].y=0;
        mem[3].x=L;mem[3].y=W;
        cin>>Point;
        for(int i=4;i<4+Point;++i)
        {
           cin>>mem[i].x>>mem[i].y;
        }
        sort(mem,mem+Point+4,cmp);
        int ans=0;
        for(int i=0;i<Point+4;++i)
        {
            for(int j=i+1,low=0,high=W,Maxl=L-mem[i].x;j<Point+4;++j)
            {
                if(mem[j].y<=high&&mem[j].y>=low)
                {
                    ans=max(ans,(high-low)*(mem[j].x-mem[i].x));
                    if(mem[j].y==mem[i].y)
                    break;
                    if(mem[j].y<mem[i].y)
                    low=mem[j].y;
                    else
                    high=mem[j].y;
                    if((high-low)*Maxl<=ans)
                    break;
                }
            }
        }
        sort(mem,mem+Point+4,cmp1);
        for(int i=0;i<Point+4;++i)
        {
            for(int j=i+1,low=0,high=L,Maxl=W-mem[i].y;j<Point+4;++j)
            {
                if(mem[j].x<=high&&mem[j].x>=low)
                {
                    ans=max(ans,(high-low)*(mem[j].y-mem[i].y));
                    if(mem[j].x==mem[i].x)
                    break;
                    if(mem[j].x<mem[i].x)
                    low=mem[j].x;
                    else
                    high=mem[j].x;
                    if((high-low)*Maxl<=ans)
                    break;
                }
            }
        }
        cout<<ans<<endl;
    }
    return 0;

}