Problem p03283 (C++)

Buggy submission (status: Runtime Error):
#include "bits/stdc++.h"
using namespace std;
typedef long long int lint;
typedef pair<lint, lint> plint;
typedef pair<double long, double long> pld;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end)                                                     \
  for (lint i = (begin), i##_end_ = (end); i < i##_end_; i++)
#define IFOR(i, begin, end)                                                    \
  for (lint i = (end)-1, i##_begin_ = (begin); i >= i##_begin_; i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first + r.first, l.second + r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first - r.first, l.second - r.second);
}
const lint MOD = 1e9 + 7, INF = 1e18;

lint N, M, Q, L, R, p, q;
lint sums[500][501];
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cin >> N >> M >> Q;
  REP(i, M) {
    cin >> L >> R;
    sums[L][R]++;
    L--;
  }
  REP(i, N) {
    REP(j, N) { sums[i][j + 1] += sums[i][j]; }
  }

  vector<lint> ans;
  REP(i, Q) {
    cin >> p >> q;
    lint sum = 0;
    REP(i, q - p + 1) { sum += (sums[p + i][q] - sums[p + i][p - 1]); }
    ans.push_back(sum);
  }
  REP(i, Q) { cout << ans[i] << endl; }
}


Fixed submission:
#include "bits/stdc++.h"
using namespace std;
typedef long long int lint;
typedef pair<lint, lint> plint;
typedef pair<double long, double long> pld;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end)                                                     \
  for (lint i = (begin), i##_end_ = (end); i < i##_end_; i++)
#define IFOR(i, begin, end)                                                    \
  for (lint i = (end)-1, i##_begin_ = (begin); i >= i##_begin_; i--)
#define REP(i, n) FOR(i, 0, n)
#define IREP(i, n) IFOR(i, 0, n)
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2>
pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first + r.first, l.second + r.second);
}
template <typename T1, typename T2>
pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) {
  return make_pair(l.first - r.first, l.second - r.second);
}
const lint MOD = 1e9 + 7, INF = 1e18;

lint N, M, Q, L, R, p, q;
lint sums[501][501];
int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cin >> N >> M >> Q;
  REP(i, M) {
    cin >> L >> R;
    sums[L][R]++;
    L--;
  }
  REP(i, N) {
    REP(j, N) { sums[i][j + 1] += sums[i][j]; }
  }

  vector<lint> ans;
  REP(i, Q) {
    cin >> p >> q;
    lint sum = 0;
    REP(i, q - p + 1) { sum += (sums[p + i][q] - sums[p + i][p - 1]); }
    ans.push_back(sum);
  }
  REP(i, Q) { cout << ans[i] << endl; }
}