poj1065 Wooden Sticks

思路：

贪心，最长下降子序列 二分。

实现：

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <windows.h>
 5 const int INF = 0x3f3f3f3f;
 6 using namespace std;
 7 struct node
 8 {
 9     int x, y;
10 };
11 node a[5005];
12 int d[5005];
13 bool cmp(const node & a, const node & b)
14 {
15     if (a.x == b.x)
16         return a.y < b.y;
17     return a.x < b.x;
18 }
19 void work(int x, int end)
20 {
21     int l = 1, r = end, m, res = INF;
22     while (l <= r)
23     {
24         m = (l + r) >> 1;
25         if (d[m] <= x)
26         {
27             r = m - 1;
28         }
29         else
30         {
31             res = m;
32             l = m + 1;
33         }
34     }
35     if (res != INF)
36         d[res + 1] = x;
37     else
38         d[1] = x;
39 }
40 int main()
41 {
42     int t, n;
43     cin >> t;
44     while (t--)
45     {
46         cin >> n;
47         for (int j = 0; j < n; j++)
48             scanf("%d %d", &a[j].x, &a[j].y);
49         sort(a, a + n, cmp);
50         int ans = 1;
51         d[1] = a[0].y;
52         for (int i = 1; i < n; i++)
53         {
54             if (a[i].y < d[ans])
55                 d[++ans] = a[i].y;
56             else
57                 work(a[i].y, ans-1);    
58         }
59         cout << ans << endl;    
60     }
61     return 0;
62 }