UVa:103 Stacking Boxes

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
struct Box
{
    int num,d[12];
};
Box p[32];
int dp[32];
int path[32];
int n,k;
bool Judge(Box &a,Box &b)
{
    for(int i=0; i<k; ++i)
        if(a.d[i]>=b.d[i]) return false;
    return true;
}
bool cmp(Box a,Box b)
{
    int i=0;
    while(a.d[i]==b.d[i]&&i<k) i++;
    if(i<k) return a.d[i]<b.d[i];
    else return a.d[i-1]<b.d[i-1];
}
int main()
{
    while(scanf("%d%d",&n,&k)!=EOF)
    {
        memset(dp,0,sizeof(dp));
        memset(path,-1,sizeof(path));
        for(int i=1; i<=n; ++i)
        {
            for(int j=0; j<k; ++j)
                scanf("%d",&p[i].d[j]);
            sort(p[i].d,p[i].d+k);
            p[i].num=i;
        }
        sort(p+1,p+n+1,cmp);
        int mx;
        for(int i=n; i>=1; --i)
        {
            mx=-1;
            bool ok=false;
            for(int j=i+1; j<=n; ++j)
                if(Judge(p[i],p[j])&&dp[j]>mx)
                {
                    mx=dp[j];
                    path[i]=j;
                    ok=true;
                }
            if(ok) dp[i]=1+mx;
            else
            {
                path[i]=0;
                dp[i]=1;
            }
        }
        mx=-1;
        int key;

        for(int i=1; i<=n; ++i)
            if(dp[i]>mx)
            {
                mx=dp[i];
                key=i;
            }
        printf("%d
",mx);
        printf("%d",p[key].num);
        key=path[key];
        while(key)
        {
            printf(" %d",p[key].num);
            key=path[key];
        }
        printf("
");
    }
    return 0;
}