Problem p01096 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
/*{{{*/ // template
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr long long LINF = numeric_limits<long long>::max() / 3;
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define sz(x) (int)(x).size()
#define debug(x) cerr << #x << ":" << x << endl
#define debug2(x, y) cerr << #x << "," << #y ":" << x << "," << y << endl
// struct fin{ fin(){ cin.tie(0); ios::sync_with_stdio(false); } } fin_;
struct Double {
  double d;
  explicit Double(double x) : d(x) {}
};
ostream &operator<<(ostream &os, const Double x) {
  os << fixed << setprecision(20) << x.d;
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (const auto &v : vec) {
    os << v << ",";
  }
  os << "]";
  return os;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &st) {
  os << "{";
  for (T v : st)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T, typename U> inline void chmax(T &x, U y) {
  if (y > x)
    x = y;
}
template <typename T, typename U> inline void chmin(T &x, U y) {
  if (y < x)
    x = y;
}
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
// constexpr double eps = 1e-14;
constexpr double eps = 1e-10;
constexpr ll mod = 1e9 + 7;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
/*}}}*/

int memo[302][302];
int w[302];

int rec(int i, int j) {
  if (i >= j)
    return 0;
  if (i + 1 == j) {
    if (abs(w[i] - w[j]) <= 1)
      return 2;
    else
      return 0;
  }
  if (memo[i][j] >= 0)
    return memo[i][j];
  int res = 0;

  if (abs(w[i] - w[j]) <= 1 and rec(i + 1, j - 1) == j - 1 - i) {
    return memo[i][j] = j - i + 1;
  }

  for (int k = i; k < j; k++) {
    int L = rec(i, k);
    int R = rec(k + 1, j);
    res = max(res, L + R);
  }
  return memo[i][j] = res;
}

void solve(int N) {
  rep(i, 302) rep(j, 302) memo[i][j] = -1;
  rep(i, N) cin >> w[i];
  cout << rec(0, N - 1) << endl;
}

int main() {
  while (1) {
    int n;
    cin >> n;
    if (n == 0)
      break;
    solve(n);
  }
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
/*{{{*/ // template
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr long long LINF = numeric_limits<long long>::max() / 3;
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define sz(x) (int)(x).size()
#define debug(x) cerr << #x << ":" << x << endl
#define debug2(x, y) cerr << #x << "," << #y ":" << x << "," << y << endl
// struct fin{ fin(){ cin.tie(0); ios::sync_with_stdio(false); } } fin_;
struct Double {
  double d;
  explicit Double(double x) : d(x) {}
};
ostream &operator<<(ostream &os, const Double x) {
  os << fixed << setprecision(20) << x.d;
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) {
  os << "[";
  for (const auto &v : vec) {
    os << v << ",";
  }
  os << "]";
  return os;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &st) {
  os << "{";
  for (T v : st)
    os << v << ",";
  os << "}";
  return os;
}
template <typename T, typename U> inline void chmax(T &x, U y) {
  if (y > x)
    x = y;
}
template <typename T, typename U> inline void chmin(T &x, U y) {
  if (y < x)
    x = y;
}
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  else
    return gcd(b, a % b);
}
// constexpr double eps = 1e-14;
constexpr double eps = 1e-10;
constexpr ll mod = 1e9 + 7;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
/*}}}*/

int memo[302][302];
int w[302];

int rec(int i, int j) {
  if (i >= j)
    return 0;
  if (i + 1 == j) {
    if (abs(w[i] - w[j]) <= 1)
      return 2;
    else
      return 0;
  }
  if (memo[i][j])
    return memo[i][j];
  int res = 0;

  if (abs(w[i] - w[j]) <= 1 and rec(i + 1, j - 1) == j - 1 - i) {
    return memo[i][j] = j - i + 1;
  }

  for (int k = i; k < j; k++) {
    int L = rec(i, k);
    int R = rec(k + 1, j);
    res = max(res, L + R);
  }
  return memo[i][j] = res;
}

void solve(int N) {
  rep(i, 302) rep(j, 302) memo[i][j] = 0;
  rep(i, N) cin >> w[i];
  cout << rec(0, N - 1) << endl;
}

int main() {
  while (1) {
    int n;
    cin >> n;
    if (n == 0)
      break;
    solve(n);
  }
}