nyist 16 矩形嵌套（最长上升子序列变形）

题目地址：http://acm.nyist.net/JudgeOnline/problem.php?pid=16

思路：放矩形的时候，正着放一次，倒着放一次，正着放肯定不会套着倒着放

AC代码：

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <cstring>
#include <climits>
#include <cmath>
#include <cctype>
const int inf = 0x3f3f3f3f;//1061109567
typedef long long LL;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
using namespace std;
struct node
{
    int x;
    int y;
}a[2010];
bool cmp(node a,node b)
{
    return a.x < b.x;
}
int dp[2010];
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        memset(dp,0,sizeof(dp));
        int n;
        scanf("%d",&n);
        for(int i=1; i<=2*n; i+=2)
        {
            int x,y;
            scanf("%d%d",&x,&y);
            a[i].x = x,a[i].y = y;
            a[i+1].x = y,a[i+1].y = x;
        }
        sort(a+1,a+2*n+1,cmp);
        dp[1] = 1;
        for(int i=2; i<=2*n; i++)
        {
            for(int j=1; j<i; j++)
            {
                if(a[i].x > a[j].x && a[i].y > a[j].y && dp[i] < dp[j])
                    dp[i] = dp[j];
            }
            dp[i]++;
        }
        int max1 = dp[1];
        for(int i=2; i<=2*n; i++)
        {
            if(dp[i] > max1)
                max1 = dp[i];
        }
        printf("%d\n",max1);
    }
    return 0;
}