Problem p02623 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#define rep(i, n) for (long long i = 0; i < n; i++)
#define Rep(i, n) for (long long i = 1; i < n; i++)
#define ll long long
#include <cmath>
#include <iomanip>
#include <iostream>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <vector>

using namespace std;
#define PI acos(-1)
using P = pair<ll, ll>;

ll ketasu(ll a) {
  ll num = 1;
  while (a / 10) {
    num++;
    a /= 10;
  }
  return num;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }

ll kosuu(ll a) {
  ll sum = 0;
  for (ll i = 1; i * i <= a; i++) {
    if (a % i == 0) {
      if (a != 1 && i * i != a) {
        sum += 2;
      } else {
        sum++;
      }
    }
  }
  return sum;
}

ll di[] = {1, 0, -1, 0};
ll dj[] = {0, -1, 0, 1};

struct UnionFind {
  vector<int> d;
  UnionFind(int n = 0) : d(n, -1) {}
  int find(int x) {
    if ((d[x]) < 0)
      return x;
    return d[x] = find(d[x]);
  }
  bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
      return false;
    if (d[x] > d[y])
      swap(x, y);
    d[x] += d[y];
    d[y] = x;
    return true;
  }
  bool same(int x, int y) { return find(x) == find(y); };
  int size(int x) { return -d[find(x)]; };
};

int deg[100005];
vector<int> to[100005];

ll n, m, q;
vector<ll> a, b, c, d;
ll ans;

void dfs(vector<ll> A) {
  if (A.size() == n + 1) {
    ll sum = 0;
    rep(i, q) {
      if (A[b[i]] - A[a[i]] == c[i])
        sum += d[i];
    }
    ans = max(ans, sum);
    return;
  }

  A.push_back(A.back());
  while (A.back() <= m) {
    dfs(A);
    A.back()++;
  }
}

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

mint f(int n) {
  if (n == 0)
    return 1;
  mint x = f(2 / n);
  x *= x;
  if (n % 2 == 1)
    x *= 2;
  return x;
}

mint choose(int n, int a) {
  mint x = 1, y = 1;
  rep(i, a) {
    x *= n - i;
    y *= a + i;
  }
  return x / y;
}

int main() {
  ll n, m, k;
  cin >> n >> m >> k;
  vector<ll> a(n);
  vector<ll> b(m);
  rep(i, n) cin >> a[i];
  rep(i, m) cin >> b[i];
  vector<ll> A(n + 1);
  vector<ll> B(m + 1);
  A[0] = 0;
  B[0] = 0;
  Rep(i, n + 1) A[i] = A[i - 1] + a[i - 1];
  Rep(i, m + 1) B[i] = B[i - 1] + b[i - 1];
  ll ans = 0;
  ll j = m;
  rep(i, n + 1) {
    ll sum = A[i];
    if (k < sum)
      break;
    while (k <= sum + B[j]) {
      j--;
    }
    ans = max(ans, i + j);
  }
  cout << ans << endl;
}


Fixed submission:
#include <bits/stdc++.h>
#define rep(i, n) for (long long i = 0; i < n; i++)
#define Rep(i, n) for (long long i = 1; i < n; i++)
#define ll long long
#include <cmath>
#include <iomanip>
#include <iostream>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <vector>

using namespace std;
#define PI acos(-1)
using P = pair<ll, ll>;

ll ketasu(ll a) {
  ll num = 1;
  while (a / 10) {
    num++;
    a /= 10;
  }
  return num;
}

ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }

ll kosuu(ll a) {
  ll sum = 0;
  for (ll i = 1; i * i <= a; i++) {
    if (a % i == 0) {
      if (a != 1 && i * i != a) {
        sum += 2;
      } else {
        sum++;
      }
    }
  }
  return sum;
}

ll di[] = {1, 0, -1, 0};
ll dj[] = {0, -1, 0, 1};

struct UnionFind {
  vector<int> d;
  UnionFind(int n = 0) : d(n, -1) {}
  int find(int x) {
    if ((d[x]) < 0)
      return x;
    return d[x] = find(d[x]);
  }
  bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
      return false;
    if (d[x] > d[y])
      swap(x, y);
    d[x] += d[y];
    d[y] = x;
    return true;
  }
  bool same(int x, int y) { return find(x) == find(y); };
  int size(int x) { return -d[find(x)]; };
};

int deg[100005];
vector<int> to[100005];

ll n, m, q;
vector<ll> a, b, c, d;
ll ans;

void dfs(vector<ll> A) {
  if (A.size() == n + 1) {
    ll sum = 0;
    rep(i, q) {
      if (A[b[i]] - A[a[i]] == c[i])
        sum += d[i];
    }
    ans = max(ans, sum);
    return;
  }

  A.push_back(A.back());
  while (A.back() <= m) {
    dfs(A);
    A.back()++;
  }
}

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod)
      x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

mint f(int n) {
  if (n == 0)
    return 1;
  mint x = f(2 / n);
  x *= x;
  if (n % 2 == 1)
    x *= 2;
  return x;
}

mint choose(int n, int a) {
  mint x = 1, y = 1;
  rep(i, a) {
    x *= n - i;
    y *= a + i;
  }
  return x / y;
}

int main() {
  ll n, m, k;
  cin >> n >> m >> k;
  vector<ll> a(n);
  vector<ll> b(m);
  rep(i, n) cin >> a[i];
  rep(i, m) cin >> b[i];
  vector<ll> A(n + 1);
  vector<ll> B(m + 1);
  A[0] = 0;
  B[0] = 0;
  Rep(i, n + 1) A[i] = A[i - 1] + a[i - 1];
  Rep(i, m + 1) B[i] = B[i - 1] + b[i - 1];
  ll ans = 0;
  ll j = m;
  rep(i, n + 1) {
    ll sum = A[i];
    if (k < sum)
      break;
    while (k < sum + B[j]) {
      j--;
    }
    ans = max(ans, i + j);
  }
  cout << ans << endl;
}