poj 3670(LIS)

// File Name: 3670.cpp
// Author: Missa_Chen
// Created Time: 2013年07月08日 星期一 21时15分34秒

#include <iostream>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#include <map>
#include <stack>
#include <set>
#include <cstdlib>
#include <vector>
#include <time.h>

using namespace std;

#define LL long long
const int inf = 0x3f3f3f3f;
const int maxn = 3e4 + 5;
int a[maxn], dp[maxn], D[maxn], len, n;
//dp[i]表示以第i个元素为子序列最后一个元素的LIS长度。
//D[len]表示上升子序列长度为len的最后一个元素。
int LIS()
{
    len = 0;
    memset(dp, 0, sizeof(dp));
    memset(D, 0, sizeof(D));
    int ret = 0;
    for (int i = 1; i <= n; ++i)
    {
        if (a[i] >= D[len])
        {
            dp[i] = len + 1;
            D[++len] = a[i];
        }
        else
        {
            int low = 1, high = len, tmp = 0;
            while (low <= high)
            {
                int mid = (low + high) >> 1;
                if (D[mid] <= a[i])
                {
                    tmp = mid;
                    low = mid + 1;
                }
                else
                    high = mid - 1;
            }
            dp[i] = tmp + 1;
            D[tmp + 1] = a[i];
        }
        ret = max(ret, dp[i]);
    }
    return ret;
}
int main()
{
    while (~scanf("%d",&n))
    {
        for (int i = 1; i <= n; ++i)
            scanf("%d", &a[i]);
        int ans = LIS();
        reverse(a + 1, a + n + 1);
        ans = max(ans, LIS());
        printf("%d
", n - ans);
    }
    return 0;
}