CF 605A(Sorting Railway Cars-贪心)

给一个序列为1~n的一个排列，每次从序列中任意取一个数扔到开头或末尾，求使数列有序的最小操作次数。

一开始以为LIS，实际不是

要求 the longest subsegment of pos, where pos[a], pos[a+1], …, pos[b] is increasing.

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<functional>
#include<iostream>
#include<cmath>
#include<cctype>
#include<ctime>
using namespace std;
#define For(i,n) for(int i=1;i<=n;i++)
#define Fork(i,k,n) for(int i=k;i<=n;i++)
#define Rep(i,n) for(int i=0;i<n;i++)
#define ForD(i,n) for(int i=n;i;i--)
#define RepD(i,n) for(int i=n;i>=0;i--)
#define Forp(x) for(int p=pre[x];p;p=next[p])
#define Forpiter(x) for(int &p=iter[x];p;p=next[p])
#define Lson (x<<1)
#define Rson ((x<<1)+1)
#define MEM(a) memset(a,0,sizeof(a));
#define MEMI(a) memset(a,127,sizeof(a));
#define MEMi(a) memset(a,128,sizeof(a));
#define INF (2139062143)
#define F (100000007)
typedef long long ll;
ll mul(ll a,ll b){return (a*b)%F;}
ll add(ll a,ll b){return (a+b)%F;}
ll sub(ll a,ll b){return (a-b+llabs(a-b)/F*F+F)%F;}
void upd(ll &a,ll b){a=(a%F+b%F)%F;}
int n;
int h[1000000]={0};
void find()
{
MEMI(h)
For(i,n) {
int p;
scanf("%d",&p);
h[p]=i;
}
int len=1,ans=1;
Fork(i,2,n)
{
if (h[i]>h[i-1]) ans=max(ans,++len);
else len=1;
}
cout<<n-ans<<endl;
}
int main()
{
//  freopen("C.in","r",stdin);
//  freopen(".out","w",stdout);
cin>>n;
find();

return 0;
}