Problem p03161 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Edge = pair<int, int>;
using Graph = vector<vector<Edge>>;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}

class UnionFind {
public:
  vector<ll> Parent;

  UnionFind(ll N) { Parent = vector<ll>(N, -1); }
  ll find(ll A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = find(Parent[A]);
  }

  ll size(ll A) { return -Parent[find(A)]; }

  bool Union(ll A, ll B) {
    A = find(A);
    B = find(B);
    if (A == B) {
      return false;
    }
    if (size(A) < size(B))
      swap(A, B);

    Parent[A] += Parent[B];
    Parent[B] = A;

    return true;
  }
};

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}

ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }

ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}

ll ceil(ll a, ll b) { return (a + b - 1) / b; }

ll dp[100010];
void solve(long long N, long long K, std::vector<long long> h) {
  for (int i = 0; i <= N; i++) {
    dp[i] = INF;
  }
  dp[1] = 0;
  for (int i = 1; i <= N; i++) {
    for (int j = 1; j <= K; j++) {
      dp[i + j] = min(dp[i] + abs(h[i - 1] - h[i + j - 1]), dp[i + j]);
    }
  }

  cout << dp[N] << endl;
}

int main() {
  long long N;
  scanf("%lld", &N);
  long long K;
  scanf("%lld", &K);
  std::vector<long long> h(N);
  for (int i = 0; i < N; i++) {
    scanf("%lld", &h[i]);
  }
  solve(N, K, std::move(h));
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Edge = pair<int, int>;
using Graph = vector<vector<Edge>>;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
const ll MOD = 1000000007;
const ll nmax = 8;
const ll INF = 1e9;
bool graph[nmax][nmax];
vector<vector<ll>> dist = vector<vector<ll>>(nmax, vector<ll>(nmax, INF));
void warshall_floyd(ll n) {
  for (size_t i = 0; i < n; i++) {
    for (size_t j = 0; j < n; j++) {
      for (size_t k = 0; k < n; k++) {
        dist[j][k] = min(dist[j][k], dist[j][i] + dist[i][k]);
      }
    }
  }
}

class UnionFind {
public:
  vector<ll> Parent;

  UnionFind(ll N) { Parent = vector<ll>(N, -1); }
  ll find(ll A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = find(Parent[A]);
  }

  ll size(ll A) { return -Parent[find(A)]; }

  bool Union(ll A, ll B) {
    A = find(A);
    B = find(B);
    if (A == B) {
      return false;
    }
    if (size(A) < size(B))
      swap(A, B);

    Parent[A] += Parent[B];
    Parent[B] = A;

    return true;
  }
};

ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
  ll g = gcd(a, b);
  return a / g * b;
}

ll mulMod(ll a, ll b) { return (((a % MOD) * (b % MOD)) % MOD); }

ll powMod(ll a, ll p) {
  if (p == 0) {
    return 1;
  } else if (p % 2 == 0) {
    ll half = powMod(a, p / 2);
    return mulMod(half, half);
  } else {
    return mulMod(powMod(a, p - 1), a);
  }
}

ll ceil(ll a, ll b) { return (a + b - 1) / b; }

ll dp[100200];
void solve(long long N, long long K, std::vector<long long> h) {
  for (int i = 0; i <= N; i++) {
    dp[i] = INF;
  }
  dp[1] = 0;
  for (int i = 1; i <= N; i++) {
    for (int j = 1; j <= K; j++) {
      dp[i + j] = min(dp[i] + abs(h[i - 1] - h[i + j - 1]), dp[i + j]);
    }
  }

  cout << dp[N] << endl;
}

int main() {
  long long N;
  scanf("%lld", &N);
  long long K;
  scanf("%lld", &K);
  std::vector<long long> h(N);
  for (int i = 0; i < N; i++) {
    scanf("%lld", &h[i]);
  }
  solve(N, K, std::move(h));
  return 0;
}