Problem p02586 (C++) — buggy submission, verdict: Runtime Error

#pragma GCC optimize("O3")
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

#define int long long
#define pb push_back
#define pf push_front
#define eb emplace_back
#define mp make_pair
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define f first
#define s second
#define sz(x) (int)x.size()
#define endl "\\n"
#define forn(i, n) for (int i = 0; i < n; ++i)
#define fore(i, l, r) for (int i = int(l); i <= int(r); ++i)
#define rep(i, begin, end) for (__typeof(end) i = (begin); i != (end); i++)
#define fill(a, value) memset(a, value, sizeof(a));
#define gcd(a, b) __gcd((a), (b))
#define watch1(x) cout << (x) << endl
#define watch2(x, y) cout << (x) << " " << (y) << endl
#define watch3(x, y, z) cout << (x) << " " << (y) << " " << (z) << endl
#define fastio                                                                 \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    oset;

const int INF = 9e18;
const int mod = 1e9 + 7;
const int N = 3005;

int i, j, k, R, C, K, a[N][N], dp[N][N][5];

void solve() {
  fill(dp, 0);
  cin >> R >> C >> K;
  for (i = 1; i <= K; i++) {
    int r, c, v;
    cin >> r >> c >> v;
    a[r][c] = v;
  }
  if (a[1][1])
    dp[1][1][1] = a[1][1];
  for (i = 1; i <= R; i++) {
    for (j = 1; j <= C; j++) {
      for (k = 0; k < 4; k++) {
        if (a[i + 1][j])
          dp[i + 1][j][1] = max(dp[i + 1][j][1], dp[i][j][k] + a[i + 1][j]);
        else
          dp[i + 1][j][0] = max(dp[i + 1][j][0], dp[i][j][k]);
        if (a[i][j + 1]) {
          dp[i][j + 1][k] = max(dp[i][j + 1][k], dp[i][j][k]);
          dp[i][j + 1][k + 1] =
              max(dp[i][j + 1][k + 1], dp[i][j][k] + a[i][j + 1]);
        } else
          dp[i][j + 1][k] = max(dp[i][j + 1][k], dp[i][j][k]);
      }
    }
  }
  int ans = 0;
  for (i = 0; i < 4; i++) {
    ans = max(ans, dp[R][C][i]);
  }
  cout << ans;
}

signed main() {
  fastio;
  int t;
  // cin>>t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}

Error: WA

Fixed submission:

#pragma GCC optimize("O3")
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

#define int long long
#define pb push_back
#define pf push_front
#define eb emplace_back
#define mp make_pair
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define f first
#define s second
#define sz(x) (int)x.size()
#define endl "\\n"
#define forn(i, n) for (int i = 0; i < n; ++i)
#define fore(i, l, r) for (int i = int(l); i <= int(r); ++i)
#define rep(i, begin, end) for (__typeof(end) i = (begin); i != (end); i++)
#define fill(a, value) memset(a, value, sizeof(a));
#define gcd(a, b) __gcd((a), (b))
#define watch1(x) cout << (x) << endl
#define watch2(x, y) cout << (x) << " " << (y) << endl
#define watch3(x, y, z) cout << (x) << " " << (y) << " " << (z) << endl
#define fastio                                                                 \\
  ios::sync_with_stdio(0);                                                     \\
  cin.tie(0);                                                                  \\
  cout.tie(0);

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    oset;

const int INF = 9e18;
const int mod = 1e9 + 7;
const int N = 305;

int i, j, k, R, C, K, a[N][N], dp[N][N][5];

void solve() {
  fill(dp, 0);
  cin >> R >> C >> K;
  for (i = 1; i <= K; i++) {
    int r, c, v;
    cin >> r >> c >> v;
    a[r][c] = v;
  }
  if (a[1][1])
    dp[1][1][1] = a[1][1];
  int ans = 0;
  for (i = 1; i <= R; i++) {
    for (j = 1; j <= C; j++) {
      for (k = 0; k < 4; k++) {
        dp[i + 1][j][0] = max(dp[i + 1][j][0], dp[i][j][k] + a[i + 1][j]);
        if (a[i][j + 1]) {
          dp[i][j + 1][k] = max(dp[i][j + 1][k], dp[i][j][k]);
          dp[i][j + 1][k + 1] =
              max(dp[i][j + 1][k + 1], dp[i][j][k] + a[i][j + 1]);
        }
        ans = max(ans, dp[i][j][k]);
      }
    }
  }
  cout << ans;
}

signed main() {
  fastio;
  int t;
  // cin>>t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}