lg1034[NOIP2002 提高组] 矩形覆盖

-> k is small <=4 -> point is limited

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1.枚举矩形包围点 500^4 舍弃 -> dfs

2.dp -> k ->无状态

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3.->枚举点加入 ( add -> cross /in_node ->if_cross )

dfs -> ans-> get()

/*
4 2
1 1
2 2
3 6
0 7

4
*/
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<bits/stdc++.h>
#define ll long long
#define ddd printf("-----------------debug\n");
using namespace std;

int n,k,x[53],y[53],ans=0x3f3f3f;

struct node
{
    int ux,uy,dx,dy,use;
    void add(int x,int y)
    {
        if(use==0)
        {
            ux=x,dx=x,uy=y,dy=y;
            use=1;
        }
        else
        {
            if(x<ux) ux=x;  
            if(x>dx) dx=x;
            if(y>uy) uy=y;  
            if(y<dy) dy=y;
        }
    }
    int in_node(int x,int y){
        if(use==0) return 0;
        if(x<ux||x>dx||y<dy||y>uy) return 0;
        return 1;
    }
    int get(){
        return (dx-ux)*(uy-dy);
    }
    int cross(struct node u){
        if(in_node(u.ux,u.uy)||in_node(u.ux,u.dy)||in_node(u.dx,u.uy)||in_node(u.dx,u.dy)) return 1;
        return 0;
    }
}g[5];

int if_cross(){
    for(int i=1;i<=k;i++)
        for(int j=i+1;j<=k;j++)
            if( g[i].cross(g[j]) || g[j].cross(g[i]) ) return 1;
    return 0;
}

void dfs(int area,int cur)
{
    if(area>=ans) return ;
    if(cur==n+1)
    {
        if(if_cross()==0&&area<ans) ans=area;
        return ;
    }
    for(int i=1;i<=k;i++)
    {
        struct node t;
        t=g[i]; g[i].add(x[cur],y[cur]);
        dfs(area-t.get()+g[i].get(),cur+1);
        g[i]=t;
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin>>n>>k;
    for(int i=1;i<=n;i++) cin>>x[i]>>y[i];
    dfs(0,1);
    cout<<ans<<endl;
    return 0;
}