POJ 1065 Wooden Sticks Greed,DP

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<sstream>
#include<cmath>
#include<climits>
#include<string>
#include<map>
#include<queue>
#include<vector>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define pb(a) push(a)
#define INF 0x1f1f1f1f
#define lson idx<<1,l,mid
#define rson idx<<1|1,mid+1,r
#define PI  3.1415926535898
template<class T> T min(const T& a,const T& b,const T& c) {
    return min(min(a,b),min(a,c));
}
template<class T> T max(const T& a,const T& b,const T& c) {
    return max(max(a,b),max(a,c));
}
void debug() {
#ifdef ONLINE_JUDGE
#else

    freopen("in.txt","r",stdin);
    freopen("d:\\out1.txt","w",stdout);
#endif
}
int getch() {
    int ch;
    while((ch=getchar())!=EOF) {
        if(ch!=‘ ‘&&ch!=‘\n‘)return ch;
    }
    return EOF;
}

const int maxn=5005;
struct node
{
    int l,w;
    bool operator < (const node &ant) const
    {
        return l<ant.l||l==ant.l&&w<ant.w;
    }
};
node da[maxn];
int vis[maxn];
int main()
{
    int t;
    scanf("%d", &t);
    for(int ca = 1; ca <= t; ca++)
    {
        int n;
        scanf("%d", &n);
        for(int i = 0; i < n; i++)
            scanf("%d%d", &da[i].l, &da[i].w);
        sort(da, da + n);
        memset(vis,0,sizeof(vis));
        int res=0;
        for(int cnt=0;;)
        {
            res++;
            int curl=-1,curw=-1;
            for(int i=0;i<n;i++)
            {
                if(!vis[i]&&da[i].l>=curl&&da[i].w>=curw)
                {
                    vis[i] = 1; cnt++;
                    curl=da[i].l;curw=da[i].w;
                }
            }
            if(cnt==n)break;
        }
        printf("%d\n",res);
    }
    return 0;
}