UVA 10534 - Wavio Sequence

/******************************************************************
***   Problem       :                                           ***
***   Author        : Shipu Ahamed (Psycho Timekiller)          ***
***   E-mail        : shipuahamed01@gmail.com                   ***
***   University    : BUBT,Dept. of CSE                         ***
***   Team          : BUBT_Psycho                               ***
***   My Blog       : http://shipuahamed.blogspot.com           ***
***   Facebook      : http://www.facebook.com/DeesheharaShipu   ***
******************************************************************/

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

#define pi 2*acos(0.0)
#define all(v) v.begin(),v.end()

//input
#define si(t) scanf("%d",&t)
#define sl(t) scanf("%lld",&t)
#define sf(t) scanf("%f",&t)
#define sd(t) scanf("%lf",&t)
#define sc(c) scanf("%c",&c)
#define sii(a,b) scanf("%d%d",&a,&b)
#define sll(a,b) scanf("%lld%lld",&a,&b)

//Output
#define P(a) printf("%d\n",a)
#define PL(a) printf("%lld\n",a)
#define PF(a) printf("%f\n",a)
#define PDB(a) printf("%lf\n",a)
#define PS(a) printf("%s\n",a)
#define PSN(a) printf("%s ",a)
#define PN(a) printf("%d ",a)
#define PLN(a) printf("%lld ",a)
#define PFN(a) printf("%f ",a)
#define PDBN(a) printf("%lf ",a)
#define PP(a,b) printf("%d %d\n",a,b)
#define PPN(a,b) printf("%d %d ",a,b)
#define PPL(a,b) printf("%lld %lld\n",a,b)
#define PPLN(a,b) printf("%lld %lld ",a,b)

#define CP(a) cout< pii;
typedef  pair piii;
typedef  pair pll;
typedef  pair psi;
typedef  vector vi;
typedef  vector vll;
typedef  vector vpii;
typedef  vector vs;
typedef  set si;
typedef  set ss;
typedef  map mii;
typedef  map mll;
typedef  map msi;

template string toString( T Number ){stringstream st;st << Number;return st.str();}
template  T SOD(T n) {__typeof(n) sum=0;for(__typeof(n) i=1;i*i<=n;i++)sum+=(n%i)?0:((i*i==n)?i:i+n/i);return sum;}


//For Define
#define forab(i,a,b) for(__typeof(b) i=(a);i<=(b);i++)
#define for0(i,n) forab(i,0,(n)-1)
#define for1(i,n) forab(i,1,n)
#define rforba(i,b,a) for(__typeof(b) i=(b);i>=(a);i--)
#define rfor0(i,n) rforba(i,(n)-1,0)
#define rfor1(i,n) rforba(i,n,1)
#define forstl(i,s) for(__typeof((s).end()) i=(s).begin(); i != (s).end(); i++)

//Debug
#define dbg(x) cout << #x << " -> " << (x) << endl;
#define dbgsarr(i,a) cout<<#a<<"["< "< "< "<>p ; return p;}

ll pow(ll a,ll b, ll m) { ll res = 1; while(b) { if(b & 1) { res = ( (res % m) * (a % m) ) %m ; } a= ((a%m) * (a%m)) %m; b >>= 1; } return res; }
ll modInverse(ll a, ll m){return pow(a,m-2,m);}

////============ CONSTANT ===============////
#define mx7   10000007
#define mx6   1000006
#define mx5   100005
#define inf   1<<30                                           //infinity value
#define eps   1e-9
#define mx    (10010)
#define mod   1000000007
////=====================================////

ll a[mx],dp[mx];

int bs(int len,int i)
{
    int low, high, mid;
    low=0;
    high=len;

    while(low<=high)
    {
        mid = ( low+high ) >> 1;
        if(dp[mid] < a[i])
        {
            low = mid+1;
        }
        else
            high = mid-1;
    }

    dp[low] = a[i];

    return low;
}

int main()
{
    int n;
    while(si(n)==1)
    {

        int lis1[mx],lis2[mx];

        for(int i=0;i=0;i--)
        {
            res = bs(m2,i);// lower_bound( dp , dp+n+1 , a[i] ) - dp;
            dp[res] = a[i] ;
            m2=max(m2,res);
            lis2[i]=m2;
        }

//        P(m2);
        int ans=0;
        for ( int i = 0 ; i < n ; i++ )
            ans = max ( ans , min(lis1[i],lis2[i]));

        P(2*ans-1);
    }
    return 0;
}
/*
7
1 4 2 3 2 4 1
*/