经典DP 嵌套矩形

    dp初级入门必学，有南阳理工学院OJ的题在此：http://acm.nyist.net/JudgeOnline/problem.php?pid=16

    简单dp，刘汝佳白书第一本，161页。稍微理解下就会了。。很easy

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

#define max(a,b)	((a)>(b)?(a):(b))
#define min(a,b)	((a)<(b)?(a):(b))
const int maxn = 15;
struct Node
{
	int x, y;
}node[maxn];
int cmp(Node a, Node b)
{
	if (a.y == b.y)
		return a.x > b.x;
	return a.y > b.y;
}

int main()
{
	int N;
	int dp[maxn];
	scanf("%d", &N);
	while (N--)
	{
		int n;
		scanf("%d", &n);
		int i, j;
		for (i=0; i<n; i++)
		{
			int tmpa, tmpb;
			scanf("%d %d", &tmpa, &tmpb);
			node[i].x = min(tmpa, tmpb);
			node[i].y = max(tmpa, tmpb);
		}
		sort(node, node+n, cmp);
		for (i=n-1; i>=0; i--)
		{
			dp[i] = 1;
			for (j=n-1; j>i; j--)
			{
				if (node[j].x < node[i].x && node[j].y <=node[i].y)
					if (dp[i] < dp[j] + 1)
						dp[i] = dp[j] + 1;
			}
		}
		int max = 0;
		for (i=0; i<n; i++)
			if (dp[i] > max)
				max = dp[i];
		printf("%d\n", max);
	}
	return 0;
}