Problem p02623 (C++)

Buggy submission (status: 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 = 2e5 + 5;

int i, n, m, k, a[N], b[N], dp1[N], dp2[N];

bool check(int mid) {
  int best = INF;
  for (i = 0; i <= n; ++i) {
    int rem = mid - i, req = dp1[i];
    if (rem <= m) {
      req += dp2[rem];
      best = min(best, req);
    }
  }
  return best <= k;
}

void solve() {
  cin >> n >> m >> k;
  for (i = 1; i <= n; ++i) {
    cin >> a[i];
    dp1[i] = a[i];
    dp1[i] += dp1[i - 1];
  }
  for (i = 1; i <= m; ++i) {
    cin >> b[i];
    dp2[i] = b[i];
    dp2[i] += dp2[i - 1];
  }
  int lo = 0, hi = m + n;
  while (lo < hi) {
    int mid = (lo + hi + 1) / 2;
    if (check(mid))
      lo = mid;
    else
      hi = mid - 1;
  }
  cout << lo;
}

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

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 = 2e5 + 5;

int i, n, m, k, a[N], b[N], dp1[N], dp2[N];

bool check(int mid) {
  int best = INF;
  for (i = 0; i <= n; ++i) {
    int rem = mid - i, req = dp1[i];
    if (rem <= m && rem >= 0) {
      req += dp2[rem];
      best = min(best, req);
    }
  }
  return best <= k;
}

void solve() {
  cin >> n >> m >> k;
  for (i = 1; i <= n; ++i) {
    cin >> a[i];
    dp1[i] = a[i];
    dp1[i] += dp1[i - 1];
  }
  for (i = 1; i <= m; ++i) {
    cin >> b[i];
    dp2[i] = b[i];
    dp2[i] += dp2[i - 1];
  }
  int lo = 0, hi = m + n;
  while (lo < hi) {
    int mid = (lo + hi + 1) / 2;
    if (check(mid))
      lo = mid;
    else
      hi = mid - 1;
  }
  cout << lo;
}

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