Problem p03472 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <sstream>
#include <string>
#include <time.h>
#include <tuple>
#include <vector>
// #include "bits/stdc++.h"
using namespace std;
// using namespace std::vector;
#define rep(i, a, b) for (ll i = (a); i < (b); ++i)
// #define M_PI 3.1415926535
#define huge 1000000007
typedef long long int ll;
ll gcd(ll a, ll b);
ll lcm(ll x, ll y);
ll bur(ll N, ll X);
std::vector<ll> enum_div(ll n);
long long comb(int n, int r);
bool IsPrime(int num);
bool dp[110][10010];
class UnionFind;

// UF木
class UnionFind {
public:
  // 親
  vector<int> Parent;

  // 初期状態
  UnionFind(int N) { Parent = vector<int>(N, -1); }

  int root(int A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = root(Parent[A]);
  }

  // サイズ確認
  int size(int A) { return -Parent[root(A)]; }

  int connect(int A, int B) {
    // root同氏をくっつける
    A = root(A);
    B = root(B);

    // 結合済み
    if (A == B) {
      return false;
    }
    // 大きいほうに小さいほうをくっつける
    if (size(A) < size(B))
      swap(A, B);

    // Aのサイズ更新
    Parent[A] += Parent[B];
    // Bの親をAに
    Parent[B] = A;

    return true;
  }
};

int main(void) {

  ll N = 0;
  ll A = 0;
  ll B = 0;
  ll C = 0;
  ll D = 0;
  ll G = 0;
  ll M = 0;
  ll H = 0;

  string S, T, U[52];
  char fi[50], fv[50];
  char board[4][4];
  ll count = 0;
  double count2 = 0;

  float min = 30000000;
  ll max = 0, max2 = 0, max3 = 0, max4 = 0;
  ll dist1 = 0;
  ll dist2 = 0;
  ll dist3 = 0;
  ll dist4 = 0;
  float now = 0;
  int tmax = 10000;
  int tmax2 = 0;
  // ll count = 0;
  // int flag = 0;
  // char temp, head, state;
  // int is = 0;
  bool start = false;
  ll left = 0, right = 0;
  cin >> N >> H;
  // cin >> S;
  // vector< vector<ll> > mat(1000, vector<ll>(1000));
  // ll mat[1000][1000] = {};
  vector<ll> an(N);
  vector<ll> bn(N);

  rep(i, 0, N) { cin >> an[i] >> bn[i]; }

  sort(an.rbegin(), an.rend());
  sort(bn.rbegin(), bn.rend());
  A = an[0];
  while (H > 0) {

    if (bn[B] > A && C < N) {
      H -= bn[B];
      bn.erase(bn.begin());
      C++;
    } else {
      H -= A;
    }

    count++;
  }

  cout << count << endl;

  return 0;
}

std::vector<ll> enum_div(ll n) // nの約数を列挙
{
  std::vector<ll> ret;
  for (int i = 1; i * i <= n; ++i) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i != 1 && i * i != n) {
        ret.push_back(n / i);
      }
    }
  }
  return ret;
}
ll bur(ll N, ll X) {
  ll pan = 1;
  ll pat = 1;
  ll burg = 0;

  if (X > burg) {
    if (N == 0)
      return pat;

    burg += pan;
    burg += bur(N - 1, X);
    burg += pat;
    burg += bur(N - 1, X);
    burg += pan;
  }

  return burg;
}

ll gcd(ll a, ll b) {

  /* 自然数 a > b を確認・入替 */
  if (a < b) {
    ll tmp = a;
    a = b;
    b = tmp;
  }
  ll x = b;
  ll y = a;
  /* ユークリッドの互除法 */
  ll r = a % b;
  while (r != 0) {
    a = b;
    b = r;
    r = a % b;
  }

  return y / b * x;
}

bool IsPrime(int num) {
  if (num < 2)
    return false;
  else if (num == 2)
    return true;
  else if (num % 2 == 0)
    return false; // 偶数はあらかじめ除く

  double sqrtNum = sqrt(num);
  for (int i = 3; i <= sqrtNum; i += 2) {
    if (num % i == 0) {
      // 素数ではない
      return false;
    }
  }

  // 素数である
  return true;
}

// 最大公約数を求める関数
ll lcm(ll x, ll y) {
  if (x == 0 || y == 0) // 引数チェック
  {
    // fprintf(stderr, "引数エラーです。\n");
    return 0;
  }

  return (x * y / gcd(x, y));
}

// combination
long long comb(int n, int r) {
  std::vector<std::vector<long long>> v(n + 1,
                                        std::vector<long long>(n + 1, 0));
  for (int i = 0; i < v.size(); i++) {
    v[i][0] = 1;
    v[i][i] = 1;
  }
  for (int j = 1; j < v.size(); j++) {
    for (int k = 1; k < j; k++) {
      v[j][k] = (v[j - 1][k - 1] + v[j - 1][k]);
    }
  }
  return v[n][r];
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <sstream>
#include <string>
#include <time.h>
#include <tuple>
#include <vector>
// #include "bits/stdc++.h"
using namespace std;
// using namespace std::vector;
#define rep(i, a, b) for (ll i = (a); i < (b); ++i)
// #define M_PI 3.1415926535
#define huge 1000000007
typedef long long int ll;
ll gcd(ll a, ll b);
ll lcm(ll x, ll y);
ll bur(ll N, ll X);
std::vector<ll> enum_div(ll n);
long long comb(int n, int r);
bool IsPrime(int num);
bool dp[110][10010];
class UnionFind;

// UF木
class UnionFind {
public:
  // 親
  vector<int> Parent;

  // 初期状態
  UnionFind(int N) { Parent = vector<int>(N, -1); }

  int root(int A) {
    if (Parent[A] < 0)
      return A;
    return Parent[A] = root(Parent[A]);
  }

  // サイズ確認
  int size(int A) { return -Parent[root(A)]; }

  int connect(int A, int B) {
    // root同氏をくっつける
    A = root(A);
    B = root(B);

    // 結合済み
    if (A == B) {
      return false;
    }
    // 大きいほうに小さいほうをくっつける
    if (size(A) < size(B))
      swap(A, B);

    // Aのサイズ更新
    Parent[A] += Parent[B];
    // Bの親をAに
    Parent[B] = A;

    return true;
  }
};

int main(void) {

  ll N = 0;
  ll A = 0;
  ll B = 0;
  ll C = 0;
  ll D = 0;
  ll G = 0;
  ll M = 0;
  ll H = 0;

  string S, T, U[52];
  char fi[50], fv[50];
  char board[4][4];
  ll count = 0;
  double count2 = 0;

  float min = 30000000;
  ll max = 0, max2 = 0, max3 = 0, max4 = 0;
  ll dist1 = 0;
  ll dist2 = 0;
  ll dist3 = 0;
  ll dist4 = 0;
  float now = 0;
  int tmax = 10000;
  int tmax2 = 0;
  // ll count = 0;
  // int flag = 0;
  // char temp, head, state;
  // int is = 0;
  bool start = false;
  ll left = 0, right = 0;
  cin >> N >> H;
  // cin >> S;
  // vector< vector<ll> > mat(1000, vector<ll>(1000));
  // ll mat[1000][1000] = {};
  vector<ll> an(N);
  vector<ll> bn(N);

  rep(i, 0, N) { cin >> an[i] >> bn[i]; }

  sort(an.rbegin(), an.rend());
  sort(bn.rbegin(), bn.rend());
  A = an[0];
  while (H > 0) {

    if (bn[B] > A && C < N) {
      H -= bn[B];
      bn.erase(bn.begin());
      C++;
    } else {
      // H -= A;
      if (H % A != 0) {
        count++;
      }

      count += H / A;
      break;
    }

    count++;
  }

  cout << count << endl;

  return 0;
}

std::vector<ll> enum_div(ll n) // nの約数を列挙
{
  std::vector<ll> ret;
  for (int i = 1; i * i <= n; ++i) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i != 1 && i * i != n) {
        ret.push_back(n / i);
      }
    }
  }
  return ret;
}
ll bur(ll N, ll X) {
  ll pan = 1;
  ll pat = 1;
  ll burg = 0;

  if (X > burg) {
    if (N == 0)
      return pat;

    burg += pan;
    burg += bur(N - 1, X);
    burg += pat;
    burg += bur(N - 1, X);
    burg += pan;
  }

  return burg;
}

ll gcd(ll a, ll b) {

  /* 自然数 a > b を確認・入替 */
  if (a < b) {
    ll tmp = a;
    a = b;
    b = tmp;
  }
  ll x = b;
  ll y = a;
  /* ユークリッドの互除法 */
  ll r = a % b;
  while (r != 0) {
    a = b;
    b = r;
    r = a % b;
  }

  return y / b * x;
}

bool IsPrime(int num) {
  if (num < 2)
    return false;
  else if (num == 2)
    return true;
  else if (num % 2 == 0)
    return false; // 偶数はあらかじめ除く

  double sqrtNum = sqrt(num);
  for (int i = 3; i <= sqrtNum; i += 2) {
    if (num % i == 0) {
      // 素数ではない
      return false;
    }
  }

  // 素数である
  return true;
}

// 最大公約数を求める関数
ll lcm(ll x, ll y) {
  if (x == 0 || y == 0) // 引数チェック
  {
    // fprintf(stderr, "引数エラーです。\n");
    return 0;
  }

  return (x * y / gcd(x, y));
}

// combination
long long comb(int n, int r) {
  std::vector<std::vector<long long>> v(n + 1,
                                        std::vector<long long>(n + 1, 0));
  for (int i = 0; i < v.size(); i++) {
    v[i][0] = 1;
    v[i][i] = 1;
  }
  for (int j = 1; j < v.size(); j++) {
    for (int k = 1; k < j; k++) {
      v[j][k] = (v[j - 1][k - 1] + v[j - 1][k]);
    }
  }
  return v[n][r];
}