Problem p02695 (C++)

Buggy submission (status: Runtime Error):
// #include "bits/stdc++.h"

#define _USE_MATH_DEFINES
#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#define rep(i, a, b) for (int i = (a), i##_len = (b); i < i##_len; i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define all(c) begin(c), end(c)

// #define int ll
#define SZ(x) ((int)(x).size())
#define pb push_back
#define mp make_pair

// typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<double, double> pdd;
typedef vector<vector<int>> mat;

template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

const int INF =
    sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;

int N, M, Q;
int A[11], B[11], C[11], D[11];
int T[11];
int ans;

void dfs(int d, int par) {
  if (d == N) {
    int res = 0;
    rep(i, 0, Q) {
      if (T[B[i]] - T[A[i]] == C[i])
        res += D[i];
    }
    chmax(ans, res);
    return;
  }
  rep(i, par, M + 1) {
    T[d] = i;
    dfs(d + 1, i);
  }
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> N >> M >> Q;

  rep(i, 0, Q) {
    cin >> A[i] >> B[i] >> C[i] >> D[i];
    A[i]--, B[i]--;
  }

  dfs(0, 1);

  cout << ans << endl;

  return 0;
}


Fixed submission:
// #include "bits/stdc++.h"

#define _USE_MATH_DEFINES
#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#define rep(i, a, b) for (int i = (a), i##_len = (b); i < i##_len; i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define all(c) begin(c), end(c)

// #define int ll
#define SZ(x) ((int)(x).size())
#define pb push_back
#define mp make_pair

// typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<double, double> pdd;
typedef vector<vector<int>> mat;

template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

const int INF =
    sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;

int N, M, Q;
int A[55], B[55], C[55], D[55];
int T[11];
int ans;

void dfs(int d, int par) {
  if (d == N) {
    int res = 0;
    rep(i, 0, Q) {
      if (T[B[i]] - T[A[i]] == C[i])
        res += D[i];
    }
    chmax(ans, res);
    return;
  }
  rep(i, par, M + 1) {
    T[d] = i;
    dfs(d + 1, i);
  }
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  cin >> N >> M >> Q;

  rep(i, 0, Q) {
    cin >> A[i] >> B[i] >> C[i] >> D[i];
    A[i]--, B[i]--;
  }

  dfs(0, 1);

  cout << ans << endl;

  return 0;
}