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 }
