Problem:
Score : 300 points

Problem Statement

There are N people numbered 1 to N. Each of them is either an honest person whose testimonies are always correct or an unkind person whose testimonies may be correct or not.

Person i gives A_i testimonies. The j-th testimony by Person i is represented by two integers x_{ij} and y_{ij}. If y_{ij} = 1, the testimony says Person x_{ij} is honest; if y_{ij} = 0, it says Person x_{ij} is unkind.

How many honest persons can be among those N people at most?

Constraints

All values in input are integers.

1 \leq N \leq 15

0 \leq A_i \leq N - 1

1 \leq x_{ij} \leq N

x_{ij} \neq i

x_{ij_1} \neq x_{ij_2} (j_1 \neq j_2)

y_{ij} = 0, 1

Input

Input is given from Standard Input in the following format:

N
A_1
x_{11} y_{11}
x_{12} y_{12}
:
x_{1A_1} y_{1A_1}
A_2
x_{21} y_{21}
x_{22} y_{22}
:
x_{2A_2} y_{2A_2}
:
A_N
x_{N1} y_{N1}
x_{N2} y_{N2}
:
x_{NA_N} y_{NA_N}

Output

Print the maximum possible number of honest persons among the N people.

Sample Input 1

3
1
2 1
1
1 1
1
2 0

Sample Output 1

2

If Person 1 and Person 2 are honest and Person 3 is unkind, we have two honest persons without inconsistencies, which is the maximum possible number of honest persons.

Sample Input 2

3
2
2 1
3 0
2
3 1
1 0
2
1 1
2 0

Sample Output 2

0

Assuming that one or more of them are honest immediately leads to a contradiction.

Sample Input 3

2
1
2 0
1
1 0

Sample Output 3

1

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

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

int main() {
  int n;
  cin >> n;
  vector<vector<pair<int, bool>>> hoge(n, vector<pair<int, bool>>(0));
  for(int i=0;i<n;i++) {
    int A;
    cin >> A;
    hoge[i].resize(A);
    for(int j=0;j<A;j++) cin >> hoge[i][j].first >> hoge[i][j].second;
  }
  int max = 0;
  for(int i=0;i<pow(2, n);i++) {
    bitset<32> kinder(i);
    bool ok = true;
    for(int j=0;j<n;j++) {
      if(kinder[j]) {
        for(int k=0;k<hoge[j].size();k++) {
          int obj = hoge[j][k].first;
          bool honest = hoge[j][k].second;
          if((kinder[obj-1] == 1 && honest) || (kinder[obj-1] == 0 && !honest)) {
            continue;
          } else {
            ok = false;
            break;
          }
        }
      }

      if(!ok) {
        break;
      }

    }

    if(ok) {
      int num = 0;
      for(int j=0;j<kinder.size();j++) {
        if(kinder[j] == 1) num++;
      }

      if(num > max) max = num;
    }
  }

  cout << max << endl;

}