Problem p03037 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#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);
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 E = 0;
  ll M = 0;
  ll K = 0;
  // ll T = 0;
  // ll M = 0;
  // ll h[400][400] = {};
  ll b[9] = {1, 7, 4, 5, 3, 2, 9, 6, 8};  // 順番の配列
  ll b2[9] = {2, 3, 4, 5, 5, 5, 6, 6, 7}; // 順番の配列

  // ll aa[20][20] = {};//sortaf
  ll c2[9] = {};

  ll d[10] = {}; // 要素数

  // ll v[3] = {};
  // ll *c, *s, *n;
  string S, T, U[52];
  char fi[50], fv[50];

  ll count = 0;
  double count2 = 0;

  ll min = 1000;
  ll max = 1;
  ll dist1 = 0;
  ll dist2 = 0;
  ll dist3 = 0;
  ll now = 0;
  int tmax = 10000;
  int tmax2 = 0;
  // int flag = 0;
  char temp, head, state;
  // int is = 0;
  bool start = false;

  // char p;

  float all = 0;
  ll amr = 0;
  ll keep = 0;
  ll lgh = 1000000007;
  // ll state = 0;
  char col = NULL;

  // ll aa[3] = {10000,10000,10000}, bb[3] = { 10000,10000,10000 }, cc[3] = {
  // 10000,10000,10000 }; ll an[3] = { 10000,10000,10000 }, bn[3] = {
  // 10000,10000,10000 }, cn[3] = { 10000,10000,10000 };

  cin >> N >> M;
  vector<double> ti(N), xi(N), yi(N);

  rep(i, 0, M) { cin >> xi[i] >> yi[i]; }
  amr = xi[0];
  keep = yi[0];

  rep(i, 0, M) {

    if (amr < xi[i])
      amr = xi[i];

    if (keep > yi[i])
      keep = yi[i];
  }

  if (keep - amr >= 0)
    cout << keep - amr + 1 << endl;
  else
    cout << 0 << endl;

  return 0;
}

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));
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#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);
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 E = 0;
  ll M = 0;
  ll K = 0;
  // ll T = 0;
  // ll M = 0;
  // ll h[400][400] = {};
  ll b[9] = {1, 7, 4, 5, 3, 2, 9, 6, 8};  // 順番の配列
  ll b2[9] = {2, 3, 4, 5, 5, 5, 6, 6, 7}; // 順番の配列

  // ll aa[20][20] = {};//sortaf
  ll c2[9] = {};

  ll d[10] = {}; // 要素数

  // ll v[3] = {};
  // ll *c, *s, *n;
  string S, T, U[52];
  char fi[50], fv[50];

  ll count = 0;
  double count2 = 0;

  ll min = 1000;
  ll max = 1;
  ll dist1 = 0;
  ll dist2 = 0;
  ll dist3 = 0;
  ll now = 0;
  int tmax = 10000;
  int tmax2 = 0;
  // int flag = 0;
  char temp, head, state;
  // int is = 0;
  bool start = false;

  // char p;

  float all = 0;
  ll amr = 0;
  ll keep = 0;
  ll lgh = 1000000007;
  // ll state = 0;
  char col = NULL;

  // ll aa[3] = {10000,10000,10000}, bb[3] = { 10000,10000,10000 }, cc[3] = {
  // 10000,10000,10000 }; ll an[3] = { 10000,10000,10000 }, bn[3] = {
  // 10000,10000,10000 }, cn[3] = { 10000,10000,10000 };

  cin >> N >> M;
  vector<double> ti(M), xi(M), yi(M);

  rep(i, 0, M) { cin >> xi[i] >> yi[i]; }
  amr = xi[0];
  keep = yi[0];

  rep(i, 0, M) {

    if (amr < xi[i])
      amr = xi[i];

    if (keep > yi[i])
      keep = yi[i];
  }

  if (keep - amr >= 0)
    cout << keep - amr + 1 << endl;
  else
    cout << 0 << endl;

  return 0;
}

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));
}