Problem p03137 (C++)

Buggy submission (status: Runtime Error):
#define NOMINMAX
#define TEST_MODE true

#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#include <random>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (a)-1; i >= (int)b; --i)
#define range(i, a, b, c) for (int i = a; c > 0 ? i < b : i > b; i += c)
#define chmax(a, b) (a = (a) < (b) ? (b) : (a))
#define chmin(a, b) (a = (a) > (b) ? (b) : (a))
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(a) begin(a), end(a)
#define ifnot(a) if (not(a))
#define int long long

#ifdef LOCAL_ENV

#if TEST_MODE == true
const bool test = true;
#define dump(x) cerr << #x << " : " << (x) << " "
#define dumpl(x) dump(x) << endl
#else
const bool test = false;
#define dump(x)
#define dumpl(x)
#endif

#else
const bool test = false;
#define dump(x)
#define dumpl(x)
#endif

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
const int INF = (int)1 << 60;
const int undefined = INF;
const ll INFL = (ll)1 << 60;
ll mod_n = (int)1e9 + 7;
const double eps = 1e-10;
typedef long double Real;
// return -1, 0, 1
int sgn(const Real &r) { return (r > eps) - (r < -eps); }
int sgn(const Real &a, const Real &b) { return sgn(a - b); }

//.....................
const int MAX = (int)2e5 + 5;

vector<string> split(const string &str, char sep) {
  vector<string> v;
  stringstream ss(str);
  string buffer;
  while (getline(ss, buffer, sep)) {
    v.push_back(buffer);
  }
  return v;
}

string join(const vector<string> &v, const string delim = 0) {
  string s;
  if (!v.empty()) {
    s += v[0];
    for (decltype(v.size()) i = 1, c = v.size(); i < c; ++i) {
      if (delim != "")
        s += delim;
      s += v[i];
    }
  }
  return s;
}

string operator*(const string &s, const int &n) {
  string res = "";
  rep(i, n) res += s;
  return res;
}

template <class InputIterator> int sum(InputIterator begin, InputIterator end) {
  return accumulate(begin, end, 0ll);
}

template <typename T> T gcd(T a, T b) {
  T c;
  while (a != 0) {
    c = a;
    a = b % a;
    b = c;
  }
  return b;
}

template <typename T> T bit_count(T N) {
  T cnt = 0;
  while (N) {
    if (N & 1)
      cnt++;
    N >>= 1;
  }
  return cnt;
}

template <typename T> void print_vec(ostream &ostream, vector<T> a) {
  rep(i, a.size() - 1) ostream << a[i] << " ";
  ostream << a.back() << endl;
}

ll pow_n(ll x, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * x;
    x = x * x;
    n >>= 1;
  }
  return res;
}

template <class T, class U> T mod_pow(T x, U n) {
  T res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * x;
    x = x * x;
    x %= mod_n;
    n >>= 1;
    res %= mod_n;
  }
  return res;
}

template <class T> T mod_rev(T a) {
  T res = 1;
  return mod_pow(a, mod_n - 2);
}

int H, W;

bool grid_ng(int y, int x) { return y < 0 || y >= H || x < 0 || x >= W; }

struct Point {
  int x, y;
  Point(int y_, int x_) : y(y_), x(x_) {}
  bool operator<(const Point &r) const {
    if (y != r.y)
      return y < r.y;
    return x < r.x;
  }
};

class Solver {
public:
  int n, m;
  vector<int> x;

  int ans() {
    int res = x.back() - x.front();
    vector<int> diff(m - 1);
    rep(i, m - 1) diff[i] = x[i + 1] - x[i];
    sort(all(diff), greater<int>());
    rep(i, min(n - 1, m)) res -= diff[i];
    return res;
  }

  void solve() {
    cin >> n >> m;
    x.resize(m);
    rep(i, m) cin >> x[i];
    sort(all(x));
    print_vec(cerr, x);
    cout << ans() << endl;
  }
};

signed main() {
  srand((unsigned int)time(NULL));
  cout << fixed << setprecision(20);
  auto ptr = new Solver();
  ptr->solve();
  delete ptr;
  // while (true) {
  //	if (cin.eof() == true) break;
  //	auto ptr = new Solver();
  //	ptr->solve();
  //	delete ptr;
  // }
  return 0;
}


Fixed submission:
#define NOMINMAX
#define TEST_MODE true

#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#include <random>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (a)-1; i >= (int)b; --i)
#define range(i, a, b, c) for (int i = a; c > 0 ? i < b : i > b; i += c)
#define chmax(a, b) (a = (a) < (b) ? (b) : (a))
#define chmin(a, b) (a = (a) > (b) ? (b) : (a))
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(a) begin(a), end(a)
#define ifnot(a) if (not(a))
#define int long long

#ifdef LOCAL_ENV

#if TEST_MODE == true
const bool test = true;
#define dump(x) cerr << #x << " : " << (x) << " "
#define dumpl(x) dump(x) << endl
#else
const bool test = false;
#define dump(x)
#define dumpl(x)
#endif

#else
const bool test = false;
#define dump(x)
#define dumpl(x)
#endif

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
const int INF = (int)1 << 60;
const int undefined = INF;
const ll INFL = (ll)1 << 60;
ll mod_n = (int)1e9 + 7;
const double eps = 1e-10;
typedef long double Real;
// return -1, 0, 1
int sgn(const Real &r) { return (r > eps) - (r < -eps); }
int sgn(const Real &a, const Real &b) { return sgn(a - b); }

//.....................
const int MAX = (int)2e5 + 5;

vector<string> split(const string &str, char sep) {
  vector<string> v;
  stringstream ss(str);
  string buffer;
  while (getline(ss, buffer, sep)) {
    v.push_back(buffer);
  }
  return v;
}

string join(const vector<string> &v, const string delim = 0) {
  string s;
  if (!v.empty()) {
    s += v[0];
    for (decltype(v.size()) i = 1, c = v.size(); i < c; ++i) {
      if (delim != "")
        s += delim;
      s += v[i];
    }
  }
  return s;
}

string operator*(const string &s, const int &n) {
  string res = "";
  rep(i, n) res += s;
  return res;
}

template <class InputIterator> int sum(InputIterator begin, InputIterator end) {
  return accumulate(begin, end, 0ll);
}

template <typename T> T gcd(T a, T b) {
  T c;
  while (a != 0) {
    c = a;
    a = b % a;
    b = c;
  }
  return b;
}

template <typename T> T bit_count(T N) {
  T cnt = 0;
  while (N) {
    if (N & 1)
      cnt++;
    N >>= 1;
  }
  return cnt;
}

template <typename T> void print_vec(ostream &ostream, vector<T> a) {
  rep(i, a.size() - 1) ostream << a[i] << " ";
  ostream << a.back() << endl;
}

ll pow_n(ll x, ll n) {
  ll res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * x;
    x = x * x;
    n >>= 1;
  }
  return res;
}

template <class T, class U> T mod_pow(T x, U n) {
  T res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * x;
    x = x * x;
    x %= mod_n;
    n >>= 1;
    res %= mod_n;
  }
  return res;
}

template <class T> T mod_rev(T a) {
  T res = 1;
  return mod_pow(a, mod_n - 2);
}

int H, W;

bool grid_ng(int y, int x) { return y < 0 || y >= H || x < 0 || x >= W; }

struct Point {
  int x, y;
  Point(int y_, int x_) : y(y_), x(x_) {}
  bool operator<(const Point &r) const {
    if (y != r.y)
      return y < r.y;
    return x < r.x;
  }
};

class Solver {
public:
  int n, m;
  vector<int> x;

  int ans() {
    int res = x.back() - x.front();
    vector<int> diff(m - 1);
    rep(i, m - 1) diff[i] = x[i + 1] - x[i];
    sort(all(diff), greater<int>());
    rep(i, min(n - 1, m - 1)) res -= diff[i];
    return res;
  }

  void solve() {
    cin >> n >> m;
    x.resize(m);
    rep(i, m) cin >> x[i];
    sort(all(x));
    print_vec(cerr, x);
    cout << ans() << endl;
  }
};

signed main() {
  srand((unsigned int)time(NULL));
  cout << fixed << setprecision(20);
  auto ptr = new Solver();
  ptr->solve();
  delete ptr;
  // while (true) {
  //	if (cin.eof() == true) break;
  //	auto ptr = new Solver();
  //	ptr->solve();
  //	delete ptr;
  // }
  return 0;
}