Problem p00040 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for (int i = x; i < n; i++)
template <class T> T RoundOff(T a) { return int(a + .5 - (a < 0)); }
template <class T, class C> void chmax(T &a, C b) {
  if (a < b)
    a = b;
}
template <class T, class C> void chmin(T &a, C b) {
  if (b < a)
    a = b;
}
template <class T, class C> pair<T, C> mp(T a, C b) { return make_pair(a, b); }

int f(int y, int a, int b) { return (a * y + b) % 26; }

int main() {
  int n;
  cin >> n;
  cin.ignore();

  rep(i, n) {
    string str;
    getline(cin, str);

    int len = str.size();

    for (int a = 0;; a++) {
      if (a % 2 != 0 && a % 13 != 0) {
        rep(b, 26) {
          // Ï·Îe[u
          int v[26];
          rep(y, 26) v[f(y, a, b)] = y;

          // Ï·
          string con = str;
          rep(in, len) if ('a' <= con[in] && con[in] <= 'z') con[in] =
              v[con[in] - 'a'] + 'a';

          // Î`FbN
          rep(in, len - 3) {
            if (con.substr(in, 4) == "that" || con.substr(in, 4) == "this") {
              cout << con << endl;
              goto ng;
            }
          }
        }
      }
    }
  ng:;
  }
  return 0;
}

Error: TLE

Fixed submission:


#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for (int i = x; i < n; i++)
template <class T> T RoundOff(T a) { return int(a + .5 - (a < 0)); }
template <class T, class C> void chmax(T &a, C b) {
  if (a < b)
    a = b;
}
template <class T, class C> void chmin(T &a, C b) {
  if (b < a)
    a = b;
}
template <class T, class C> pair<T, C> mp(T a, C b) { return make_pair(a, b); }

int f(int y, int a, int b) { return (a * y + b) % 26; }

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

  rep(i, n) {
    string str;
    cin.sync();
    getline(cin, str);
    int len = str.size();

    for (int a = 0;; a++) {
      if (a % 2 != 0 && a % 13 != 0) {
        rep(b, 26) {
          // Ï·Îe[u
          int v[26];
          rep(y, 26) v[f(y, a, b)] = y;

          // Ï·
          string con = str;
          rep(in, len) if ('a' <= con[in] && con[in] <= 'z') con[in] =
              v[con[in] - 'a'] + 'a';

          // Î`FbN
          rep(in, len - 3) {
            if (con.substr(in, 4) == "that" || con.substr(in, 4) == "this") {
              cout << con << endl;
              goto ng;
            }
          }
        }
      }
    }
  ng:;
  }
  return 0;
}