POJ 3903 Stock Exchange

#include <cstdio>   
#include<iostream>
#include <cstring>   
#include <algorithm>   
using namespace std;  
  
int a[100005],c[100005],n;  
  
int bin(int size,int k)  
{  
    int l = 1,r = size;  
    while(l<=r)  
    {  
        int mid = (l+r)/2;  
        if(k>c[mid])  
            l = mid+1;  
        else  
            r = mid-1;  
    }  
    return l;  
}  
  
int LIS()  
{  
    int i,cnt=0,k;  
    for(i = 1; i<=n; i++)  
    {  
        if(cnt == 0 || a[i]>c[cnt])  
           c[++cnt] = a[i];  
        else  
        {  
           k = bin(cnt,a[i]);  
           c[k] = a[i];  
        }  
    }  
    return cnt;  
}  
  
int main()  
{  
    long i;  
    while(~scanf("%d",&n))  
    {  
        for(i = 1; i<=n; i++)  
            scanf("%d",&a[i]);  
        printf("%d\n",LIS());  
    }  
  
    return 0;  
}