Problem p02596 (C++)

Buggy submission (status: Time Limit Exceeded):
/*

                         YATIN KWATRA                       _03_08_14


Let's Hoop..



                             __oooo
       //  /    o
     / /  |      o
    | /  |__     o
   | |   __/    o
   | |  /  oooo
  | /  |  _______________________
 | |   | |_______________________|
||    |___ \__/\_/\_/\/\/\/\/\/\/
||    |    \ \/\/\/\/\/\/\/\/\/
||    \     \ \/\/\/\/\/\/\/\/
| |    |    |  \/\/\/\/\/\/\/
 | |    |   |   \/\/\/\/\/\/
  | |    \_/    |\/\/\/\/\/|
   \ \     \__  |/\/\/\/\/\|
    |         \
   |           |
   |           |
   |           |
   |           |
    |          |
    |         |
     |________|
     |________|
    ||         |
   | |          |
  |  /          |
 |  /          /
 /\|__________|
|   /       /
|  |       /
| |       |
 \ |      \
  \ \      \
    \ \     |
      \ \    |
        \ \  |_
          \\_/ \
           |    |
           |   /
           |  |
           |_/



HOOPER_4_LYF..

*/

// AC BAKSHI RABBA

// #pragma GCC optimize "trapv"

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define FIO                                                                    \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
#define endl "\n"
#define fo(i, a, b) for (int i = a; i <= b; i++)
#define rfo(i, a, b) for (int i = a; i >= b; i--)
#define vii vector<int>
#define vll vector<ll>
#define pq priority_queue
#define uom unordered_map
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back
#define pob pop_back
#define ff first
#define ss second
#define pii pair<int, int>
#define pll pair<long, long>
#define mll map<ll, ll>
#define mii map<int, int>
#define vvii vector<vii>
#define vvll vector<vll>
#define mod 1000000007
#define MIN -1e9
#define pi 3.1415926535897932384626433832795

using namespace std;

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

/*

   -> Check For Overflows
   -> Out of Bounds
   -> Initialisations of global arrays and variables
   -> Read the Question and the sample test cases carefully
   -> Its not Always Complex, Try to simplify
   -> write it down and try to solve
   -> Have Faith in urself and in ur approach
   -> If it seems totally out of reach, switch to next :)
   -> And Come Back later, if possible ..



o- - -  \o          __|
   o/   /|          vv`\
  /|     |              |
   |    / \_            |
  / \   |               |
 /  |                   |


   Thats what I call a Tappu / Blocked_shot / Rejection...


   Time to Code Now.....
*/

void solve() {

  int n;
  cin >> n;

  if (!(n & 1) and !(n % 5)) {
    cout << -1 << endl;
    return;
  }

  ll no = 7;
  int ans = 0;

  while (1) {

    ans++;

    if (!(no % n)) {
      cout << ans << endl;
      return;
    }

    no %= n;
    no = no * 10 + 7;
  }
}

int main() {

  FIO INPUT();

  int t;
  t = 1;
  // cin >> t;

  fo(i, 0, t - 1) { solve(); }
  return 0;
}


Fixed submission:
/*

                         YATIN KWATRA                       _03_08_14


Let's Hoop..



                             __oooo
       //  /    o
     / /  |      o
    | /  |__     o
   | |   __/    o
   | |  /  oooo
  | /  |  _______________________
 | |   | |_______________________|
||    |___ \__/\_/\_/\/\/\/\/\/\/
||    |    \ \/\/\/\/\/\/\/\/\/
||    \     \ \/\/\/\/\/\/\/\/
| |    |    |  \/\/\/\/\/\/\/
 | |    |   |   \/\/\/\/\/\/
  | |    \_/    |\/\/\/\/\/|
   \ \     \__  |/\/\/\/\/\|
    |         \
   |           |
   |           |
   |           |
   |           |
    |          |
    |         |
     |________|
     |________|
    ||         |
   | |          |
  |  /          |
 |  /          /
 /\|__________|
|   /       /
|  |       /
| |       |
 \ |      \
  \ \      \
    \ \     |
      \ \    |
        \ \  |_
          \\_/ \
           |    |
           |   /
           |  |
           |_/



HOOPER_4_LYF..

*/

// AC BAKSHI RABBA

// #pragma GCC optimize "trapv"

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define ull unsigned long long
#define FIO                                                                    \
  ios_base::sync_with_stdio(false);                                            \
  cin.tie(NULL);                                                               \
  cout.tie(NULL);
#define endl "\n"
#define fo(i, a, b) for (int i = a; i <= b; i++)
#define rfo(i, a, b) for (int i = a; i >= b; i--)
#define vii vector<int>
#define vll vector<ll>
#define pq priority_queue
#define uom unordered_map
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back
#define pob pop_back
#define ff first
#define ss second
#define pii pair<int, int>
#define pll pair<long, long>
#define mll map<ll, ll>
#define mii map<int, int>
#define vvii vector<vii>
#define vvll vector<vll>
#define mod 1000000007
#define MIN -1e9
#define pi 3.1415926535897932384626433832795

using namespace std;

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

/*

   -> Check For Overflows
   -> Out of Bounds
   -> Initialisations of global arrays and variables
   -> Read the Question and the sample test cases carefully
   -> Its not Always Complex, Try to simplify
   -> write it down and try to solve
   -> Have Faith in urself and in ur approach
   -> If it seems totally out of reach, switch to next :)
   -> And Come Back later, if possible ..



o- - -  \o          __|
   o/   /|          vv`\
  /|     |              |
   |    / \_            |
  / \   |               |
 /  |                   |


   Thats what I call a Tappu / Blocked_shot / Rejection...


   Time to Code Now.....
*/

void solve() {

  int n;
  cin >> n;

  if (!(n & 1) or !(n % 5)) {
    cout << -1 << endl;
    return;
  }

  ll no = 7;
  int ans = 0;

  while (1) {

    ans++;

    if (!(no % n)) {
      cout << ans << endl;
      return;
    }

    no %= n;
    no = no * 10 + 7;
  }
}

int main() {

  FIO INPUT();

  int t;
  t = 1;
  // cin >> t;

  fo(i, 0, t - 1) { solve(); }
  return 0;
}