View Compilation Error

0_0_39553672_27080.cpp: In function 'void solve()':
0_0_39553672_27080.cpp:149:26: error: no match for 'operator[]' (operand types are 'matrix' and 'std::tuple_element<0, std::pair<int, int> >::type' {aka 'int'})
  149 |                         t[v][i] = w;
      |                          ^