poj 3670(LIS) 

 1 // File Name: 3670.cpp
 2 // Author: Missa_Chen
 3 // Created Time: 2013年07月08日 星期一 21时15分34秒
 4 
 5 #include <iostream>
 6 #include <string>
 7 #include <algorithm>
 8 #include <cstdio>
 9 #include <cstring>
10 #include <cmath>
11 #include <queue>
12 #include <map>
13 #include <stack>
14 #include <set>
15 #include <cstdlib>
16 #include <vector>
17 #include <time.h>
18 
19 using namespace std;
20 
21 #define LL long long
22 const int inf = 0x3f3f3f3f;
23 const int maxn = 3e4 + 5;
24 int a[maxn], dp[maxn], D[maxn], len, n;
25 //dp[i]表示以第i个元素为子序列最后一个元素的LIS长度。
26 //D[len]表示上升子序列长度为len的最后一个元素。
27 int LIS()
28 {
29     len = 0;
30     memset(dp, 0, sizeof(dp));
31     memset(D, 0, sizeof(D));
32     int ret = 0;
33     for (int i = 1; i <= n; ++i)
34     {
35         if (a[i] >= D[len])
36         {
37             dp[i] = len + 1;
38             D[++len] = a[i];
39         }
40         else
41         {
42             int low = 1, high = len, tmp = 0;
43             while (low <= high)
44             {
45                 int mid = (low + high) >> 1;
46                 if (D[mid] <= a[i])
47                 {
48                     tmp = mid;
49                     low = mid + 1;
50                 }
51                 else
52                     high = mid - 1;
53             }
54             dp[i] = tmp + 1;
55             D[tmp + 1] = a[i];
56         }
57         ret = max(ret, dp[i]);
58     }
59     return ret;
60 }
61 int main()
62 {
63     while (~scanf("%d",&n))
64     {
65         for (int i = 1; i <= n; ++i)
66             scanf("%d", &a[i]);
67         int ans = LIS();
68         reverse(a + 1, a + n + 1);
69         ans = max(ans, LIS());
70         printf("%d\n", n - ans);
71     }
72     return 0;
73 }

 

posted @ 2013-07-08 23:52  Missa  阅读(287)  评论(0)    收藏  举报