Longest Increasing Subsequence with O(N log K)

// LIS -- O(N log K)

#include<bits/stdc++.h>
#define sze 100

using namespace std;

const int inf=9999;

int seq[sze+5], lisseq[sze+5] , n , I[sze+5], L[sze+5];

int Binary_Search(int lo, int hi, int itm)
{
    int mid;

    while(lo <= hi)
    {
        mid = (lo + hi) / 2;

        if(I[mid] < itm)
        {
            lo = mid+1;
        }

        else
        {
            hi = mid-1;
        }
    }

    return lo;
}

int LIS()
{
    //memset(L, 1, sizeof(L));

    int i , r , len=0 , llen=0;

    for(i=0; i<n; i++)
    {
        r = Binary_Search(0, len, seq[i]);

        I[r] = seq[i];
        L[llen++] = r;

        if(len < r)
        {
            len = r;
        }
    }

    return len;
}

void find_sequence(int mxlen)
{
    int i=0 , j;

    for(j=1; j<n; j++)
    {
        if(L[i] < L[j])
        {
            i = j;
        }
    }

    int top = L[i];

    top--;

    lisseq[top] = seq[i];

    for(j=i-1; j>=0; j--)
    {
        if(seq[j] < seq[i] and L[j] == L[i] - 1)
        {
            i = j;

            top--;

            lisseq[top] = seq[i];
        }
    }

    cout << "LIS Sequence: ";

    for(i=0; i<mxlen; i++)
    {
        cout << lisseq[i] << " ";
    }
}

int main()
{
    while(cin >> n)
    {
        int ilen=0;

         I[ilen++] = -inf;

        for(int i=0;i<n;i++)
        {
            cin >> seq[i];

            I[ilen++] = seq[i];
        }

        int lislen = LIS();

        find_sequence(lislen);

        cout << "LIS Length: " << lislen << "\n";
    }

    return 0;
}