ZOJ 1025 Wooden Sticks

　　题目大意：有n个木棍，分别具有长度li和重量wi。对于木棍s1和s2，若l1<=l2且w1<=w2，则s1、s2可构成单调递增序列。求n个木棍中这样序列的个数。

　　最先的想法是，先排序，然后一遍一遍扫描，直到全部处理完。

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 using namespace std;
 #define MAXN 5000+10

 struct Wooden
 {
     int l, w;
     bool operator < (const Wooden& x) const
     {
         if (l != x.l)   return l < x.l;
         else return w < x.w;
     }
 };
 Wooden wooden[MAXN];
 bool processed[MAXN];

 int main()
 {
 #ifdef LOCAL
     freopen("in", "r", stdin);
 #endif
     int T;
     scanf("%d", &T);
     while (T--)
     {
         int n;
         scanf("%d", &n);
         for (int i = ; i < n; i++)
             scanf("%d%d", &wooden[i].l, &wooden[i].w);
         sort(wooden, wooden+n);
         int time = ;
         memset(processed, , sizeof(processed));
         int remain = n;
         while (remain > )
         {
             time++;
             int prel = -, prew = -;
             for (int i = ; i < n; i++)
                 if (!processed[i] && wooden[i].l >= prel && wooden[i].w >= prew)
                 {
                     processed[i] = true;
                     remain--;
                     prel = wooden[i].l;
                     prew = wooden[i].w;
                 }
         }
         printf("%d\n", time);
     }
     return ;
 }

　　看到网上说可以通过求解最长（严格）递减序列的答案，可是怎么都理解不了，留待以后吧...