Here is the link of problem at atcoder:

I tried it with a naive recursion approach. It's running good with the testcases in my pc but getting RE in atcoder compiler. I have no clue how it is getting RE.

Here is the solution

#include<bits/stdc++.h>
using namespace std;
int N,sum=0,mn=INT_MAX,h[100006];
int recur(int i,int sum)
{
   if(N>=4)
   {
       return mn=min(sum,mn);
   }
    else
    {
       recur(i+1,sum+abs(h[i+1]-h[i]));
       recur(i+2,sum+abs(h[i+2]-h[i]));
    }
}
int main()
{
    int n,i,j,k;
    cin>>N;
    for(i=1;i<=N;i++)
    {
        cin>>h[i];
    }
    cout<<recur(1,0)<<endl;
    return 0;
}