Problem p03160 (C++)

Buggy submission (status: Runtime Error):
// gauravsinghh
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long int
#define ld long double
#define db double
#define pii pair<int, int>
#define pll pair<long long, long long>
#define sii set<int>
#define sll set<long long>
#define vii vector<int>
#define vll vector<long long>
#define mii map<int, int>
#define mll map<long long, long long>
#define lob lower_bound
#define upb upper_bound
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define ins insert
#define mp make_pair
#define w(t)                                                                   \
  cin >> t;                                                                    \
  while (t--)
#define on cout << "\n"
#define o2(a, b) cout << a << " " << b
#define os cout << " "
#define bitcount __builtin_popcount
#define gcd __gcd
#define endl "\n"
#define present(s, x) (s.find(x) != s.end())
#define cpresent(s, x) (find(all(s), x) != s.end())
#define ford(container, it)                                                    \
  for (__typeof(container.begin()) it = container.begin();                     \
       it != container.end(); it++)
#define fors(container, it, a, b)                                              \
  for (__typeof(container.begin()) it = a; it != b; it++)
#define MOD 1000000007
#define EPSILON 1e-9
#define PI 3.14159265358979323846
#define inf 999999999999999999
#define siz 100005
#define SIZ 1000005
#define SIZE 200005
#define fbo find_by_order
#define ook order_of_key
#define sz(s) (int)s.size()
#define mem(n, m) memset(n, m, sizeof(n))
#define rep(i, n) for (ll i = 0; i < n; i++)
#define ren(i, n) for (ll i = n - 1; i >= 0; i--)
#define all(x) x.begin(), x.end()
#define fo(i, a, b) for (ll i = a; i <= b; i++)
#define ffo(i, a, b) for (ll i = a; i >= b; i--)
#define MAX 100005
#define IOS                                                                    \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
typedef tree<ll, null_type, less<ll>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds;

void io_set() {
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}

ll n, dp[100005], a[100005];

ll func() {
  dp[0] = 0;
  dp[1] = abs(a[1] - a[0]);
  fo(i, 2, n) {
    dp[i] =
        min(dp[i - 1] + abs(a[i] - a[i - 1]), dp[i - 2] + abs(a[i] - a[i - 2]));
  }
  return dp[n - 1];
}

signed main() {
  IOS io_set();
  cin >> n;
  rep(i, n) { cin >> a[i]; }
  cout << func() << endl;
  return 0;
}


Fixed submission:
// gauravsinghh
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long int
#define ld long double
#define db double
#define pii pair<int, int>
#define pll pair<long long, long long>
#define sii set<int>
#define sll set<long long>
#define vii vector<int>
#define vll vector<long long>
#define mii map<int, int>
#define mll map<long long, long long>
#define lob lower_bound
#define upb upper_bound
#define ff first
#define ss second
#define pb push_back
#define pf push_front
#define ins insert
#define mp make_pair
#define w(t)                                                                   \
  cin >> t;                                                                    \
  while (t--)
#define on cout << "\n"
#define o2(a, b) cout << a << " " << b
#define os cout << " "
#define bitcount __builtin_popcount
#define gcd __gcd
#define endl "\n"
#define present(s, x) (s.find(x) != s.end())
#define cpresent(s, x) (find(all(s), x) != s.end())
#define ford(container, it)                                                    \
  for (__typeof(container.begin()) it = container.begin();                     \
       it != container.end(); it++)
#define fors(container, it, a, b)                                              \
  for (__typeof(container.begin()) it = a; it != b; it++)
#define MOD 1000000007
#define EPSILON 1e-9
#define PI 3.14159265358979323846
#define inf 999999999999999999
#define siz 100005
#define SIZ 1000005
#define SIZE 200005
#define fbo find_by_order
#define ook order_of_key
#define sz(s) (int)s.size()
#define mem(n, m) memset(n, m, sizeof(n))
#define rep(i, n) for (ll i = 0; i < n; i++)
#define ren(i, n) for (ll i = n - 1; i >= 0; i--)
#define all(x) x.begin(), x.end()
#define fo(i, a, b) for (ll i = a; i <= b; i++)
#define ffo(i, a, b) for (ll i = a; i >= b; i--)
#define MAX 100005
#define IOS                                                                    \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
typedef tree<ll, null_type, less<ll>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds;

void io_set() {
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
}

ll n, dp[100005], a[100005];

ll func() {
  dp[0] = 0;
  dp[1] = abs(a[1] - a[0]);
  fo(i, 2, n) {
    dp[i] =
        min(dp[i - 1] + abs(a[i] - a[i - 1]), dp[i - 2] + abs(a[i] - a[i - 2]));
  }
  return dp[n - 1];
}

signed main() {
  IOS
          // io_set();
          cin >>
      n;
  rep(i, n) { cin >> a[i]; }
  cout << func() << endl;
  return 0;
}