Problem p03891 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
#define REP(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for (int(i) = (a)-1; (i) >= 0; (i)--)
#define FORR(i, a, b) for (int(i) = (a)-1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template <typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

VVI func(VVI mas, int sum) {
  mas[2][1] = sum - mas[0][1] - mas[1][1];
  mas[2][0] = sum - mas[0][2] - mas[1][1];
  mas[2][2] = sum - mas[2][0] - mas[2][1];
  mas[1][0] = sum - mas[0][0] - mas[2][0];
  mas[1][2] = sum - mas[1][0] - mas[1][1];
  REP(i, 3) REP(j, 3) {
    if (mas[i][j] < 0)
      return VVI(0);
  }
  REP(i, 3) if (accumulate(ALL(mas[i]), 0) != sum) return VVI(0);
  REP(j, 3) {
    int buf = 0;
    REP(i, 3) buf += mas[i][j];
    if (buf != sum)
      return VVI(0);
  }
  int buf = 0;
  REP(i, 3) buf += mas[i][i];
  if (buf != sum)
    return VVI(0);
  buf = 0;
  REP(i, 3) buf += mas[3 - i - 1][i];
  if (buf != sum)
    return VVI(0);
  return mas;
}

int main(void) {
  VVI mas(3, VI(3));
  int a, b, c;
  cin >> a >> b >> c;
  mas[0][0] = a;
  mas[0][1] = b;
  mas[1][1] = c;
  VVI ans;
  FOR(i, 1, 1000) {
    mas[0][2] = i;
    int sum = a + b + i;
    ans = func(mas, sum);
    if (ans != VVI(0))
      break;
  }
  REP(i, 3) {
    REP(j, 3) { cout << (j ? " " : "") << ans[i][j]; }
    cout << endl;
  }
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
#define REP(i, n) for (int(i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int(i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for (int(i) = (a)-1; (i) >= 0; (i)--)
#define FORR(i, a, b) for (int(i) = (a)-1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template <typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

VVI func(VVI mas, int sum) {
  mas[2][1] = sum - mas[0][1] - mas[1][1];
  mas[2][0] = sum - mas[0][2] - mas[1][1];
  mas[2][2] = sum - mas[2][0] - mas[2][1];
  mas[1][0] = sum - mas[0][0] - mas[2][0];
  mas[1][2] = sum - mas[1][0] - mas[1][1];
  // REP(i, 3)REP(j, 3) {
  //     if (mas[i][j] < 0) return VVI(0);
  // }
  REP(i, 3) if (accumulate(ALL(mas[i]), 0) != sum) return VVI(0);
  REP(j, 3) {
    int buf = 0;
    REP(i, 3) buf += mas[i][j];
    if (buf != sum)
      return VVI(0);
  }
  int buf = 0;
  REP(i, 3) buf += mas[i][i];
  if (buf != sum)
    return VVI(0);
  buf = 0;
  REP(i, 3) buf += mas[3 - i - 1][i];
  if (buf != sum)
    return VVI(0);
  return mas;
}

int main(void) {
  VVI mas(3, VI(3));
  int a, b, c;
  cin >> a >> b >> c;
  mas[0][0] = a;
  mas[0][1] = b;
  mas[1][1] = c;
  VVI ans;
  FOR(i, 1, 1000) {
    mas[0][2] = i;
    int sum = a + b + i;
    ans = func(mas, sum);
    if (ans != VVI(0))
      break;
  }
  REP(i, 3) {
    REP(j, 3) { cout << (j ? " " : "") << ans[i][j]; }
    cout << endl;
  }
}