Problem p03831 (C++)

Buggy submission (status: Runtime Error):
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

#include <unordered_map>
#include <unordered_set>

using namespace std;

#define all(c) ((c).begin()), ((c).end())
#define dump(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define REP(i, a, b) for (int i = a; i < (int)(b); i++)
#define rep(i, n) REP(i, 0, n)
#define mp make_pair
#define fst first
#define snd second
#define pb push_back
#define debug(fmt, ...) fprintf(stderr, fmt "\n", ##__VA_ARGS__)

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int INF = 1 << 30;
const double EPS = 1e-10;

double zero(double d) { return d < EPS ? 0.0 : d; }
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << '(' << p.first << ',' << p.second << ')';
}

template <typename T> ostream &operator<<(ostream &os, const vector<T> &a) {
  os << '[';
  rep(i, a.size()) os << (i ? " " : "") << a[i];
  return os << ']';
}

string toString(int i) {
  stringstream ss;
  ss << i;
  return ss.str();
}

const int MOD = 1000000007;
// a^k
ll fpow(ll a, ll k, int M) {
  ll res = 1ll;
  ll x = a;
  while (k != 0) {
    if ((k & 1) == 1)
      res = (res * x) % M;
    x = (x * x) % M;
    k >>= 1;
  }
  return res;
}

struct prepare {
  prepare() {
    cout.setf(ios::fixed, ios::floatfield);
    cout.precision(8);
    ios_base::sync_with_stdio(false);
  }
} _prepare;

int main() {
  ll N, A, B;
  cin >> N >> A >> B;

  vi X(N);
  rep(i, N) cin >> X[i];

  vi diff(N - 1);
  rep(i, N) diff[i] = X[i + 1] - X[i];

  ll sm = 0;
  rep(i, N - 1) {
    if (A * diff[i] <= B)
      sm += A * diff[i];
    else
      sm += B;
  }

  cout << sm << endl;

  return 0;
}


Fixed submission:
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

#include <unordered_map>
#include <unordered_set>

using namespace std;

#define all(c) ((c).begin()), ((c).end())
#define dump(c) cerr << "> " << #c << " = " << (c) << endl;
#define iter(c) __typeof((c).begin())
#define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++)
#define REP(i, a, b) for (int i = a; i < (int)(b); i++)
#define rep(i, n) REP(i, 0, n)
#define mp make_pair
#define fst first
#define snd second
#define pb push_back
#define debug(fmt, ...) fprintf(stderr, fmt "\n", ##__VA_ARGS__)

typedef unsigned int uint;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<vi> vvi;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int INF = 1 << 30;
const double EPS = 1e-10;

double zero(double d) { return d < EPS ? 0.0 : d; }
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << '(' << p.first << ',' << p.second << ')';
}

template <typename T> ostream &operator<<(ostream &os, const vector<T> &a) {
  os << '[';
  rep(i, a.size()) os << (i ? " " : "") << a[i];
  return os << ']';
}

string toString(int i) {
  stringstream ss;
  ss << i;
  return ss.str();
}

const int MOD = 1000000007;
// a^k
ll fpow(ll a, ll k, int M) {
  ll res = 1ll;
  ll x = a;
  while (k != 0) {
    if ((k & 1) == 1)
      res = (res * x) % M;
    x = (x * x) % M;
    k >>= 1;
  }
  return res;
}

struct prepare {
  prepare() {
    cout.setf(ios::fixed, ios::floatfield);
    cout.precision(8);
    ios_base::sync_with_stdio(false);
  }
} _prepare;

int main() {
  ll N, A, B;
  cin >> N >> A >> B;

  vi X(N);
  rep(i, N) cin >> X[i];

  vi diff(N - 1);
  rep(i, N - 1) diff[i] = X[i + 1] - X[i];

  ll sm = 0;
  rep(i, N - 1) {
    if (A * diff[i] <= B)
      sm += A * diff[i];
    else
      sm += B;
  }

  cout << sm << endl;

  return 0;
}