View Compilation Error

0_0_24799296_17565.cpp: In member function 'void Node::Update(int, int, bool)':
0_0_24799296_17565.cpp:41:16: error: lvalue required as increment operand
     this->cover++;
                ^
0_0_24799296_17565.cpp:44:16: error: lvalue required as decrement operand
     this->cover--;
                ^
0_0_24799296_17565.cpp: In member function 'double Node::Query(int, int)':
0_0_24799296_17565.cpp:57:17: error: cannot convert 'double*' to 'double' in return
    return this->len;
                 ^