Problem p03263 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#include <cinttypes>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

using namespace std;

#define countof(a) (sizeof(a) / sizeof(*a))

#define vi vector<int>
#define vvi vector<vector<int>>
#define vpi vector<pi>
#define pi pair<int, int>
#define fi first
#define se second
#define all(n) n.begin(), n.end()

#define FOR(var, to) for (register s64 var = 0; var < (s64)to; var++)
#define FROMTO(var, from, to)                                                  \
  for (register s64 var = from; var <= (s64)to; var++)

#define INIT(var) FOR(i, countof(var)) var[i] = 0
#define INPUT(var) FOR(i, countof(var)) var[i] = ri()

#define SORT(v) qsort(v, countof(v), sizeof(*v), int_less)
#define SORTT(v) qsort(v, countof(v), sizeof(*v), int_greater)
#define QSORT(v, b) qsort(v, countof(v), sizeof(*v), b)

#define MOD 1000000007
#define INF (1 << 30)

typedef uint8_t u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;
typedef int8_t s8;
typedef int16_t s16;
typedef int32_t s32;
typedef int64_t s64;

template <int mod> struct ModInt {
  int x;
  ModInt() : x(0) {}
  ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }
  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
  bool operator==(const ModInt &p) const { return x == p.x; }
  bool operator!=(const ModInt &p) const { return x != p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    return ModInt(u);
  }
  friend ostream &operator<<(ostream &os, const ModInt<mod> &p) {
    return os << p.x;
  }
  friend istream &operator>>(istream &is, ModInt<mod> &a) {
    long long x;
    is >> x;
    a = ModInt<mod>(x);
    return (is);
  }
};
typedef ModInt<MOD> mint;

struct UnionFind {
  vi data;
  UnionFind(int size) : data(size, -1) {}
  bool unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x != y) {
      if (data[y] < data[x])
        swap(x, y);
      data[x] += data[y];
      data[y] = x;
    }
    return x != y;
  }
  bool find(int x, int y) { return root(x) == root(y); }
  int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
  int size(int x) { return -data[root(x)]; }
  bool united() {
    int comroot = -1;
    FOR(i, data.size()) {
      if (comroot != -1 && root(i) != comroot)
        return false;
      comroot = root(i);
    }
    return true;
  }
};

static inline int ri() {
  int a;
  scanf("%d", &a);
  return a;
}

static inline s64 rs64() {
  s64 a;
  scanf("%" SCNd64, &a);
  return a;
}

static inline void wi(int a) { printf("%d", a); }

static inline void wu64(u64 a) { printf("%" PRIu64, a); }

static inline void ws64(s64 a) { printf("%" PRId64, a); }

int int_less(const void *a, const void *b) {
  return (*((const int *)a) - *((const int *)b));
}
int int_greater(const void *a, const void *b) {
  return (*((const int *)b) - *((const int *)a));
}

int main() {
  int h, w;
  cin >> h >> w;
  int a[h][w];
  FOR(j, h) INPUT(a[j]);
  /*
  FOR(i,h) {
      FOR(j,w) cout << a[i][j] << " ";
      cout << endl;
  }*/
  int res1[h * w];
  int res2[h * w];
  int res3[h * w];
  int res4[h * w];
  int res = 0;
  FOR(i, h) {
    FOR(j, w) {
      if (a[i][j] % 2) {
        res1[res] = i + 1;
        res2[res] = j + 1;
        a[i][j]--;
        if (j == w - 1) {
          res3[res] = i + 2;
          res4[res] = j + 1;
          a[i + 1][j]++;
        } else {
          res3[res] = i + 1;
          res4[res] = j + 2;
          a[i][j + 1]++;
        }
        res++;
      }
    }
  }
  cout << res << endl;
  FOR(i, res) printf("%d %d %d %d\n", res1[i], res2[i], res3[i], res4[i]);

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
#include <cinttypes>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

using namespace std;

#define countof(a) (sizeof(a) / sizeof(*a))

#define vi vector<int>
#define vvi vector<vector<int>>
#define vpi vector<pi>
#define pi pair<int, int>
#define fi first
#define se second
#define all(n) n.begin(), n.end()

#define FOR(var, to) for (register s64 var = 0; var < (s64)to; var++)
#define FROMTO(var, from, to)                                                  \
  for (register s64 var = from; var <= (s64)to; var++)

#define INIT(var) FOR(i, countof(var)) var[i] = 0
#define INPUT(var) FOR(i, countof(var)) var[i] = ri()

#define SORT(v) qsort(v, countof(v), sizeof(*v), int_less)
#define SORTT(v) qsort(v, countof(v), sizeof(*v), int_greater)
#define QSORT(v, b) qsort(v, countof(v), sizeof(*v), b)

#define MOD 1000000007
#define INF (1 << 30)

typedef uint8_t u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;
typedef int8_t s8;
typedef int16_t s16;
typedef int32_t s32;
typedef int64_t s64;

template <int mod> struct ModInt {
  int x;
  ModInt() : x(0) {}
  ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }
  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
  bool operator==(const ModInt &p) const { return x == p.x; }
  bool operator!=(const ModInt &p) const { return x != p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    return ModInt(u);
  }
  friend ostream &operator<<(ostream &os, const ModInt<mod> &p) {
    return os << p.x;
  }
  friend istream &operator>>(istream &is, ModInt<mod> &a) {
    long long x;
    is >> x;
    a = ModInt<mod>(x);
    return (is);
  }
};
typedef ModInt<MOD> mint;

struct UnionFind {
  vi data;
  UnionFind(int size) : data(size, -1) {}
  bool unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x != y) {
      if (data[y] < data[x])
        swap(x, y);
      data[x] += data[y];
      data[y] = x;
    }
    return x != y;
  }
  bool find(int x, int y) { return root(x) == root(y); }
  int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
  int size(int x) { return -data[root(x)]; }
  bool united() {
    int comroot = -1;
    FOR(i, data.size()) {
      if (comroot != -1 && root(i) != comroot)
        return false;
      comroot = root(i);
    }
    return true;
  }
};

static inline int ri() {
  int a;
  scanf("%d", &a);
  return a;
}

static inline s64 rs64() {
  s64 a;
  scanf("%" SCNd64, &a);
  return a;
}

static inline void wi(int a) { printf("%d", a); }

static inline void wu64(u64 a) { printf("%" PRIu64, a); }

static inline void ws64(s64 a) { printf("%" PRId64, a); }

int int_less(const void *a, const void *b) {
  return (*((const int *)a) - *((const int *)b));
}
int int_greater(const void *a, const void *b) {
  return (*((const int *)b) - *((const int *)a));
}

int main() {
  int h, w;
  cin >> h >> w;
  int a[h][w];
  FOR(j, h) INPUT(a[j]);
  /*
  FOR(i,h) {
      FOR(j,w) cout << a[i][j] << " ";
      cout << endl;
  }*/
  int res1[h * w];
  int res2[h * w];
  int res3[h * w];
  int res4[h * w];
  int res = 0;
  FOR(i, h) {
    FOR(j, w) {
      if (i == h - 1 && j == w - 1)
        continue;
      if (a[i][j] % 2) {
        res1[res] = i + 1;
        res2[res] = j + 1;
        a[i][j]--;
        if (j == w - 1) {
          res3[res] = i + 2;
          res4[res] = j + 1;
          a[i + 1][j]++;
        } else {
          res3[res] = i + 1;
          res4[res] = j + 2;
          a[i][j + 1]++;
        }
        res++;
      }
    }
  }
  cout << res << endl;
  FOR(i, res) printf("%d %d %d %d\n", res1[i], res2[i], res3[i], res4[i]);

  return 0;
}