Problem p02586 (C++) — buggy submission, verdict: Time Limit Exceeded

#ifndef LOCAL
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization("unroll-loops")
#endif
#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
using namespace std;
using namespace __gnu_pbds;
#define sim template <class c
#define int long long
#define ris return *this
#define dor > debug &operator<<
#define eni(x)                                                                 \\
  sim > typename enable_if<sizeof dud<c>(0) x 1, debug &>::type operator<<(    \\
            c i) {
sim > struct rge {
  c b, e;
};
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c *x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
  ~debug() { cerr << '\\n'; }
  eni(!=) cerr << boolalpha << i;
  ris;
} eni(==) ris << range(begin(i), end(i));
}
sim, class b dor(pair<b, c> d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
  sim dor(const c &) { ris; }
#endif
}
;
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define fastio                                                                 \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(0);
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef long long ll;
const ll MOD = 1e9 + 7;
const ll N = 2e5 + 10;
const ll INF = 1e18 + 10;
int n, m, k;
int a[3001][3001];
int dp[3001][3001][4];
int dfs(int x, int y, int cur) {
  if (x == n && y == m) {
    return 0;
  }
  if (x == n)
    return 0;
  if (y == m)
    return 0;
  if (dp[x][y][cur] != -1)
    return dp[x][y][cur];
  int ans = 0;
  if (a[x][y] == 0) {
    ans = max(dfs(x + 1, y, 0), dfs(x, y + 1, cur));
  } else {
    int value = a[x][y];
    if (cur < 3) {
      ans = max(ans, value + dfs(x, y + 1, cur + 1));
      ans = max(ans, value + dfs(x + 1, y, 0));
    }
    ans = max(ans, dfs(x, y + 1, cur));
    ans = max(ans, dfs(x + 1, y, 0));
  }
  return dp[x][y][cur] = ans;
}
signed main() {
  fastio memset(dp, -1, sizeof dp);
  cin >> n >> m >> k;
  for (int i = 0; i < k; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    x--, y--;
    a[x][y] = z;
  }
  int ans = dfs(0, 0, 0);
  cout << ans << endl;
  return 0;
}

Error: TLE

Fixed submission:

#ifndef LOCAL
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization("unroll-loops")
#endif
#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
using namespace std;
using namespace __gnu_pbds;
#define sim template <class c
#define int long long
#define ris return *this
#define dor > debug &operator<<
#define eni(x)                                                                 \\
  sim > typename enable_if<sizeof dud<c>(0) x 1, debug &>::type operator<<(    \\
            c i) {
sim > struct rge {
  c b, e;
};
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c *x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
  ~debug() { cerr << '\\n'; }
  eni(!=) cerr << boolalpha << i;
  ris;
} eni(==) ris << range(begin(i), end(i));
}
sim, class b dor(pair<b, c> d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
  sim dor(const c &) { ris; }
#endif
}
;
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define fastio                                                                 \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(0);
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set;
typedef long long ll;
const ll MOD = 1e9 + 7;
const ll N = 2e5 + 10;
const ll INF = 1e18 + 10;
int n, m, k;
map<pair<int, int>, int> mp;
int dp[3001][3001][4];
int dfs(int x, int y, int cur) {
  if (x == n && y == m) {
    return 0;
  }
  if (x == n)
    return 0;
  if (y == m)
    return 0;
  if (dp[x][y][cur] != -1)
    return dp[x][y][cur];
  auto it = mp.find(make_pair(x, y));
  int ans = 0;
  if (it == mp.end()) {
    ans = max(dfs(x + 1, y, 0), dfs(x, y + 1, cur));
  } else {
    int value = it->second;
    if (cur < 3) {
      ans = max(ans, value + dfs(x, y + 1, cur + 1));
      ans = max(ans, value + dfs(x + 1, y, 0));
    }
    ans = max(ans, dfs(x, y + 1, cur));
    ans = max(ans, dfs(x + 1, y, 0));
  }
  return dp[x][y][cur] = ans;
}
signed main() {
  fastio memset(dp, -1, sizeof dp);
  cin >> n >> m >> k;
  for (int i = 0; i < k; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    x--, y--;
    mp[make_pair(x, y)] = z;
  }
  int ans = dfs(0, 0, 0);
  cout << ans << endl;
  return 0;
}