Problem p03230 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
typedef long double ld;
const ll INF = 1e+14;
typedef pair<int, int> P;
#define stop                                                                   \
  char nyaa;                                                                   \
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(), c.end()
#define pb push_back

void Yes() {
  cout << "Yes" << endl;
  exit(0);
}

void No() {
  cout << "No" << endl;
  exit(0);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int N;
  cin >> N;
  int n = 2 * N, k = -1;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (i + 1 == n / i) {
        k = i + 1;
      }
    }
  }
  if (k == -1)
    No();
  cout << "Yes" << endl;
  cout << k << endl;
  vector<int> S[400];
  int u = 0, d = 1;
  rep1(i, N) {
    S[u].pb(i);
    S[d].pb(i);
    d++;
    if (d == k) {
      u++;
      d = u + 1;
    }
  }
  rep(i, k) {
    cout << k - 1 << " ";
    rep(j, k - 1) { cout << S[i][j] << " "; }
    cout << endl;
  }
  return 0;
}

Fixed submission:
#include <algorithm>
#include <bitset>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
typedef long double ld;
const ll INF = 1e+14;
typedef pair<int, int> P;
#define stop                                                                   \
  char nyaa;                                                                   \
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(), c.end()
#define pb push_back

void Yes() {
  cout << "Yes" << endl;
  exit(0);
}

void No() {
  cout << "No" << endl;
  exit(0);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int N;
  cin >> N;
  int n = 2 * N, k = -1;
  for (int i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      if (i + 1 == n / i) {
        k = i + 1;
      }
    }
  }
  if (k == -1)
    No();
  cout << "Yes" << endl;
  cout << k << endl;
  vector<int> S[1000];
  int u = 0, d = 1;
  rep1(i, N) {
    S[u].pb(i);
    S[d].pb(i);
    d++;
    if (d == k) {
      u++;
      d = u + 1;
    }
  }
  rep(i, k) {
    cout << k - 1 << " ";
    rep(j, k - 1) { cout << S[i][j] << " "; }
    cout << endl;
  }
  return 0;
}