longest increasing subsequence(O(nlogn))

Question

LIS:wikipedia

There is one thing that I can\'t understand:

why is X[M[i]] a non-decreasing sequence?

Answer 1

You can surely check this video for explanation:

https://www.youtube.com/watch?v=nf3YG4CnTbg&feature=youtu.be

My code for nlogn approch is:

int n;
cin>>n;//LENGTH OF ARRAY
vectorv(n);
for(int i=0;i>v[i];
}
vectord(n+1,INT_MAX);//AUXILLARY ARRAY
for(int i=0;i<=n;i++){
    *lower_bound(d.begin(),d.end(),v[i])=v[i];
}
for(int i=0;i