Problem p03835 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
using namespace std;

#define rep(i, s, n) for (int i = (int)s; i < (int)n; i++)
#define ll long long
#define pb push_back
#define eb emplace_back
#define All(x) x.begin(), x.end()
#define Range(x, i, j) x.begin() + i, x.begin() + j
#define lbidx(x, y) lower_bound(x.begin(), x.end(), y) - x.begin()
#define ubidx(x, y) upper_bound(x.begin(), x.end(), y) - x.begin()
#define llbidx(x, y, z)                                                        \
  lower_bound(x.begin(), x.end(), z) -                                         \
      lower_bound(x.begin(), x.end(), y) // 二要素間の距離
#define deg2rad(deg) ((((double)deg) / ((double)360) * 2 * M_PI))
#define rad2deg(rad) ((((double)rad) / (double)2 / M_PI) * (double)360)
#define Find(set, element) set.find(element) != set.end()
#define Decimal(x) printf("%.10f\n", x) // 小数点を10桁まで表示
// debug用
#define PrintVec(x)                                                            \
  for (auto elementPrintVec : x) {                                             \
    cout << elementPrintVec << " ";                                            \
  }                                                                            \
  cout << endl;

typedef pair<int, int> PI;
typedef pair<ll, ll> PLL;

int POWINT(int x, int n) {
  int ret = 1;
  rep(i, 0, n) ret *= x;
  return ret;
};

ll POWLL(int x, int n) {
  ll ret = 1;
  rep(i, 0, n) ret *= x;
  return ret;
};

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int k, s;
  cin >> k >> s;

  int ans = 0;
  rep(x, 0, k + 1) {
    rep(y, 0, k + 1) {
      rep(z, 0, k + 1) {
        if (x + y + z == s)
          ans++;
      }
    }
  }

  cout << ans << endl;

  return 0;
};


Fixed submission:
#include <bits/stdc++.h>
using namespace std;

#define rep(i, s, n) for (int i = (int)s; i < (int)n; i++)
#define ll long long
#define pb push_back
#define eb emplace_back
#define All(x) x.begin(), x.end()
#define Range(x, i, j) x.begin() + i, x.begin() + j
#define lbidx(x, y) lower_bound(x.begin(), x.end(), y) - x.begin()
#define ubidx(x, y) upper_bound(x.begin(), x.end(), y) - x.begin()
#define llbidx(x, y, z)                                                        \
  lower_bound(x.begin(), x.end(), z) -                                         \
      lower_bound(x.begin(), x.end(), y) // 二要素間の距離
#define deg2rad(deg) ((((double)deg) / ((double)360) * 2 * M_PI))
#define rad2deg(rad) ((((double)rad) / (double)2 / M_PI) * (double)360)
#define Find(set, element) set.find(element) != set.end()
#define Decimal(x) printf("%.10f\n", x) // 小数点を10桁まで表示
// debug用
#define PrintVec(x)                                                            \
  for (auto elementPrintVec : x) {                                             \
    cout << elementPrintVec << " ";                                            \
  }                                                                            \
  cout << endl;

typedef pair<int, int> PI;
typedef pair<ll, ll> PLL;

int POWINT(int x, int n) {
  int ret = 1;
  rep(i, 0, n) ret *= x;
  return ret;
};

ll POWLL(int x, int n) {
  ll ret = 1;
  rep(i, 0, n) ret *= x;
  return ret;
};

template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int k, s;
  cin >> k >> s;

  int ans = 0;
  rep(x, 0, k + 1) {
    rep(y, 0, k + 1) {
      int xy = x + y;
      int z = s - xy;
      if (0 <= z && z <= k)
        ans++;
    }
  }

  cout << ans << endl;

  return 0;
};