Frog 2 - AtCoder - TopDown

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> ii;

#define vt vector
#define eb emplace_back
#define pb push_back
#define F first
#define S second
#define f(i, s, f) for(int i = s; i < f; ++i)
#define fd(i, s, f) for(int i = s; i >= f; --i)
#define r(x, ns) for(auto &x : ns)
#define s(x) int(x.size())
#define be(ns) ns.begin(), ns.end()
#define rbe(ns) ns.rbegin(), ns.rend()

const int INF = 1<<30, MOD = 1e9+7;
const int mxn = 1e5+2, mxm = 102;

int n, k;
vt<int> vs(mxn);
vt<ll> memo(mxn, -1);

ll g(int i) {
  if(i == n) return 0;
  if(memo[i] != -1) return memo[i];
  ll ans = INF, v;
  f(j,1,min(n-i, k)+1) {
    v = abs(vs[i+j] - vs[i]);
    ans = min(ans, v + g(i+j));
  }
  return memo[i] = ans;
}

int main() {
  cin>>n>>k;
  f(i,1,n+1) cin>>vs[i];
  cout<<g(1)<<'\n';
}