View Compilation Error

0_0_21962348_4145.cpp: In function 'int main()':
0_0_21962348_4145.cpp:24:24: error: no match for 'operator[]' (operand types are 'int [100010]' and 'std::vector<int>')
                 ++ flag[G[i]];
                        ^
0_0_21962348_4145.cpp:34:24: error: no match for 'operator[]' (operand types are 'int [100010]' and 'std::vector<int>')
                 -- flag[G[i]];
                        ^