Problem p03203 (C++)

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

#define NDEBUG
#include <cassert>

typedef long long ll;
typedef long double Double;
typedef unsigned long long ull;
typedef pair<int, int> ii;
typedef pair<ll, ll> llll;
typedef pair<double, double> dd;

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ii> vii;
typedef vector<vector<ii>> vvii;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<llll> vllll;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<long double> vD;

#define sz(a) int((a).size())
#define pb push_back
#define eb emplace_back
#define FOR(var, from, to) for (int var = (from); var <= (to); ++var)
#define rep(var, n) for (int var = 0; var < (n); ++var)
#define rep1(var, n) for (int var = 1; var <= (n); ++var)
#define repC2(vari, varj, n)                                                   \
  for (int vari = 0; vari < (n)-1; ++vari)                                     \
    for (int varj = vari + 1; varj < (n); ++varj)
#define repC3(vari, varj, vark, n)                                             \
  for (int vari = 0; vari < (n)-2; ++vari)                                     \
    for (int varj = vari + 1; varj < (n)-1; ++varj)                            \
      for (int vark = varj + 1; vark < (n); ++vark)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define tr(i, c) for (auto i = (c).begin(); i != (c).end(); ++i)
#define found(s, e) ((s).find(e) != (s).end())
#define mset(arr, val) memset(arr, val, sizeof(arr))
#define mid(x, y) ((x) + ((y) - (x)) / 2)
#define IN(x, a, b) ((a) <= (x) && (x) <= (b))
#define cons make_pair
#define clamp(v, lo, hi) min(max(v, lo), hi)

template <class T> inline void amin(T &a, T const &b) { a = min(a, b); }
template <class T> inline void amax(T &a, T const &b) { a = max(a, b); }
template <typename X, typename T> auto vectors(X x, T a) {
  return vector<T>(x, a);
}
template <typename X, typename Y, typename Z, typename... Zs>
auto vectors(X x, Y y, Z z, Zs... zs) {
  auto cont = vectors(y, z, zs...);
  return vector<decltype(cont)>(x, cont);
}

inline ll square(ll x) { return x * x; }
inline ll gcd(ll a, ll b) {
  while (a)
    swap(a, b %= a);
  return b;
}
template <typename T> inline T mod(T a, T b) { return ((a % b) + b) % b; }

int solve(int H, int W, int N, vi &x, vi &y) {
  vvi ps(H);
  rep(i, N) {
    if (x[i] >= y[i]) {
      ps[x[i]].pb(y[i]);
    }
  }

  int rightmost = 0;
  int best = H;
  rep(i, H) {
    if (ps[1 + i].empty()) {
      rightmost++;
    } else {
      sort(ALL(ps[1 + i]));
      if (ps[1 + i][0] <= rightmost) {
        best = 1 + i;
        break;
      } else if (rightmost + 1 == ps[1 + i][0]) {
        ;
      } else {
        rightmost++;
      }
    }
  }

  return best;
}

int main() {
  int H, W, N;
  scanf("%d%d%d", &H, &W, &N);
  vi x(N), y(N);
  rep(i, N) {
    scanf("%d%d", &x[i], &y[i]);
    --x[i];
    --y[i];
  }
  cout << solve(H, W, N, x, y) << endl;
  return 0;
}


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

#define NDEBUG
#include <cassert>

typedef long long ll;
typedef long double Double;
typedef unsigned long long ull;
typedef pair<int, int> ii;
typedef pair<ll, ll> llll;
typedef pair<double, double> dd;

typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ii> vii;
typedef vector<vector<ii>> vvii;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<llll> vllll;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<long double> vD;

#define sz(a) int((a).size())
#define pb push_back
#define eb emplace_back
#define FOR(var, from, to) for (int var = (from); var <= (to); ++var)
#define rep(var, n) for (int var = 0; var < (n); ++var)
#define rep1(var, n) for (int var = 1; var <= (n); ++var)
#define repC2(vari, varj, n)                                                   \
  for (int vari = 0; vari < (n)-1; ++vari)                                     \
    for (int varj = vari + 1; varj < (n); ++varj)
#define repC3(vari, varj, vark, n)                                             \
  for (int vari = 0; vari < (n)-2; ++vari)                                     \
    for (int varj = vari + 1; varj < (n)-1; ++varj)                            \
      for (int vark = varj + 1; vark < (n); ++vark)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define tr(i, c) for (auto i = (c).begin(); i != (c).end(); ++i)
#define found(s, e) ((s).find(e) != (s).end())
#define mset(arr, val) memset(arr, val, sizeof(arr))
#define mid(x, y) ((x) + ((y) - (x)) / 2)
#define IN(x, a, b) ((a) <= (x) && (x) <= (b))
#define cons make_pair
#define clamp(v, lo, hi) min(max(v, lo), hi)

template <class T> inline void amin(T &a, T const &b) { a = min(a, b); }
template <class T> inline void amax(T &a, T const &b) { a = max(a, b); }
template <typename X, typename T> auto vectors(X x, T a) {
  return vector<T>(x, a);
}
template <typename X, typename Y, typename Z, typename... Zs>
auto vectors(X x, Y y, Z z, Zs... zs) {
  auto cont = vectors(y, z, zs...);
  return vector<decltype(cont)>(x, cont);
}

inline ll square(ll x) { return x * x; }
inline ll gcd(ll a, ll b) {
  while (a)
    swap(a, b %= a);
  return b;
}
template <typename T> inline T mod(T a, T b) { return ((a % b) + b) % b; }

int solve(int H, int W, int N, vi &x, vi &y) {
  vvi ps(H + 1);
  rep(i, N) {
    if (x[i] >= y[i]) {
      ps[x[i]].pb(y[i]);
    }
  }

  int rightmost = 0;
  int best = H;
  rep(i, H) {
    if (ps[1 + i].empty()) {
      rightmost++;
    } else {
      sort(ALL(ps[1 + i]));
      if (ps[1 + i][0] <= rightmost) {
        best = 1 + i;
        break;
      } else if (rightmost + 1 == ps[1 + i][0]) {
        ;
      } else {
        rightmost++;
      }
    }
  }

  return best;
}

int main() {
  int H, W, N;
  scanf("%d%d%d", &H, &W, &N);
  vi x(N), y(N);
  rep(i, N) {
    scanf("%d%d", &x[i], &y[i]);
    --x[i];
    --y[i];
  }
  cout << solve(H, W, N, x, y) << endl;
  return 0;
}