Problem p02793 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\t" << b << endl
#define p3(a, b, c) idp cout << a << "\t" << b << "\t" << c << endl
#define p4(a, b, c, d)                                                         \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << endl
#define p5(a, b, c, d, e)                                                      \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << endl
#define p6(a, b, c, d, e, f)                                                   \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << endl
#define p7(a, b, c, d, e, f, g)                                                \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << endl
#define p8(a, b, c, d, e, f, g, h)                                             \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i)                                          \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << "\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j)                                      \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << "\t" << i << "\t" << j << endl
#define foreach(it, v)                                                         \
  for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                                                             \
  idp {                                                                        \
    rep(i, n) { cout << x[i] << " "; }                                         \
    puts("");                                                                  \
  }
#define dump2(x, n)                                                            \
  idp {                                                                        \
    rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; }            \
    puts("");                                                                  \
  }
#define dumpi(x)                                                               \
  idp {                                                                        \
    foreach (it, x) {                                                          \
      cout << (*it) << " ";                                                    \
    }                                                                          \
    puts("");                                                                  \
  }
#define dumpi2(x)                                                              \
  idp {                                                                        \
    foreach (it, x) {                                                          \
      cout << "[" << (it)->F << " , " << (it)->S << "] ";                      \
    }                                                                          \
    puts("");                                                                  \
  }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                                                        \
  rep(i, h) {                                                                  \
    rep(j, w) cout << a[i][j] << " ";                                          \
    puts("");                                                                  \
  }

typedef pair<li, li> PI;

#define PRIME_MAX 1000001

bool isp[PRIME_MAX] = {false};
vector<li> primes;

inline void prime_init() {
  repp(i, 2, PRIME_MAX) isp[i] = true;
  repp(i, 2, sqrt(PRIME_MAX) + 2) {
    if (isp[i]) {
      for (li j = 2; i * j < PRIME_MAX; j++) {
        isp[i * j] = false;
      }
    }
  }
  rep(i, PRIME_MAX) if (isp[i]) primes.pb(i);
}

inline unordered_map<li, li> decom(li x) {
  vector<PI> res;
  rep(i, sz(primes)) {
    li tres = 0;
    while (x % primes[i] == 0) {
      tres++;
      x /= primes[i];
    }
    if (tres > 0)
      res.pb({primes[i], tres});
    if (x <= 1)
      break;
  }
  if (x > 1) {
    res.pb({x, 1});
  }
  unordered_map<li, li> ress;
  for (auto &&v : res) {
    ress[v.F] = v.S;
  }
  return ress;
}

li n;
li a[10010];

inline void lcm(unordered_map<li, li> &x, const unordered_map<li, li> &y) {
  for (auto &&kv : y) {
    x[kv.F] = max(x[kv.F], kv.S);
  }
}

// a x + b y = gcd(a, b)
inline li extgcd(li a, li b, li &x, li &y) {
  li g = a;
  x = 1;
  y = 0;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= (a / b) * x;
  return g;
}

inline li invMod(li a) {
  li x, y;
  if (extgcd(a, MOD, x, y) == 1)
    return (x + MOD) % MOD;
  else
    return 0; // unsolvable
}

inline li calc(unordered_map<li, li> &x) {
  li res = 1;
  for (auto &&kv : x) {
    rep(i, kv.S) { res = (res * kv.F) % MOD; }
  }
  return res;
}

int main() {
  prime_init();
  cin >> n;

  unordered_map<li, li> l;
  rin {
    cin >> a[i];
    lcm(l, decom(a[i]));
  }

  li ll = calc(l);
  li res = 0;
  rin { res += ll * invMod(a[i]) % MOD; }
  cout << res % MOD << endl;

  return 0;
}

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

#define li long long int
#define rep(i, to) for (li i = 0; i < ((li)(to)); i++)
#define repp(i, start, to) for (li i = (li)(start); i < ((li)(to)); i++)
#define pb push_back
#define sz(v) ((li)(v).size())
#define bgn(v) ((v).begin())
#define eend(v) ((v).end())
#define allof(v) (v).begin(), (v).end()
#define dodp(v, n) memset(v, (li)n, sizeof(v))
#define bit(n) (1ll << (li)(n))
#define mp(a, b) make_pair(a, b)
#define rin rep(i, n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1

#define idp if (DBGP)
#define F first
#define S second
#define p2(a, b) idp cout << a << "\t" << b << endl
#define p3(a, b, c) idp cout << a << "\t" << b << "\t" << c << endl
#define p4(a, b, c, d)                                                         \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << endl
#define p5(a, b, c, d, e)                                                      \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << endl
#define p6(a, b, c, d, e, f)                                                   \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << endl
#define p7(a, b, c, d, e, f, g)                                                \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << endl
#define p8(a, b, c, d, e, f, g, h)                                             \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << endl
#define p9(a, b, c, d, e, f, g, h, i)                                          \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << "\t" << i << endl
#define p10(a, b, c, d, e, f, g, h, i, j)                                      \
  idp cout << a << "\t" << b << "\t" << c << "\t" << d << "\t" << e << "\t"    \
           << f << "\t" << g << "\t" << h << "\t" << i << "\t" << j << endl
#define foreach(it, v)                                                         \
  for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
#define p2p(x) idp p2((x).F, (x).S)
#define dump(x, n)                                                             \
  idp {                                                                        \
    rep(i, n) { cout << x[i] << " "; }                                         \
    puts("");                                                                  \
  }
#define dump2(x, n)                                                            \
  idp {                                                                        \
    rep(i, n) { cout << "[" << x[i].F << " , " << x[i].S << "] "; }            \
    puts("");                                                                  \
  }
#define dumpi(x)                                                               \
  idp {                                                                        \
    foreach (it, x) {                                                          \
      cout << (*it) << " ";                                                    \
    }                                                                          \
    puts("");                                                                  \
  }
#define dumpi2(x)                                                              \
  idp {                                                                        \
    foreach (it, x) {                                                          \
      cout << "[" << (it)->F << " , " << (it)->S << "] ";                      \
    }                                                                          \
    puts("");                                                                  \
  }

#define read2d(a, w, h) rep(i, h) rep(j, w) cin >> a[i][j]
#define dump2d(a, w, h)                                                        \
  rep(i, h) {                                                                  \
    rep(j, w) cout << a[i][j] << " ";                                          \
    puts("");                                                                  \
  }

typedef pair<li, li> PI;

#define PRIME_MAX 1000001

bool isp[PRIME_MAX] = {false};
vector<li> primes;

inline void prime_init() {
  repp(i, 2, PRIME_MAX) isp[i] = true;
  repp(i, 2, sqrt(PRIME_MAX) + 2) {
    if (isp[i]) {
      for (li j = 2; i * j < PRIME_MAX; j++) {
        isp[i * j] = false;
      }
    }
  }
  rep(i, PRIME_MAX) if (isp[i]) primes.pb(i);
}

inline unordered_map<li, li> decom(li x) {
  vector<PI> res;
  rep(i, sz(primes)) {
    if (primes[i] > 1000) {
      break;
    }
    li tres = 0;
    while (x % primes[i] == 0) {
      tres++;
      x /= primes[i];
    }
    if (tres > 0)
      res.pb({primes[i], tres});
    if (x <= 1)
      break;
  }
  if (x > 1) {
    res.pb({x, 1});
  }
  unordered_map<li, li> ress;
  for (auto &&v : res) {
    ress[v.F] = v.S;
  }
  return ress;
}

li n;
li a[10010];

inline void lcm(unordered_map<li, li> &x, const unordered_map<li, li> &y) {
  for (auto &&kv : y) {
    x[kv.F] = max(x[kv.F], kv.S);
  }
}

// a x + b y = gcd(a, b)
inline li extgcd(li a, li b, li &x, li &y) {
  li g = a;
  x = 1;
  y = 0;
  if (b != 0)
    g = extgcd(b, a % b, y, x), y -= (a / b) * x;
  return g;
}

inline li invMod(li a) {
  li x, y;
  if (extgcd(a, MOD, x, y) == 1)
    return (x + MOD) % MOD;
  else
    return 0; // unsolvable
}

inline li calc(unordered_map<li, li> &x) {
  li res = 1;
  for (auto &&kv : x) {
    rep(i, kv.S) { res = (res * kv.F) % MOD; }
  }
  return res;
}

int main() {
  prime_init();
  cin >> n;

  unordered_map<li, li> l;
  rin {
    cin >> a[i];
    lcm(l, decom(a[i]));
  }

  li ll = calc(l);
  li res = 0;
  rin { res += ll * invMod(a[i]) % MOD; }
  cout << res % MOD << endl;

  return 0;
}