C ++ Unoromeded_Map с использованием пользовательского типа класса в качестве ключа ⇐ C++

[Anonymous]

Я пытаюсь использовать пользовательский класс в качестве ключа для Unoromeded_map < /code>, например, следующее: < /p>

#include
#include
#include

using namespace std;

class node;
class Solution;

class Node {
public:
int a;
int b;
int c;
Node(){}
Node(vector v) {
sort(v.begin(), v.end());
a = v[0];
b = v[1];
c = v[2];
}

bool operator==(Node i) {
if ( i.a==this->a && i.b==this->b &&i.c==this->c ) {
return true;
} else {
return false;
}
}
};

int main() {
unordered_map m;

vector v;
v.push_back(3);
v.push_back(8);
v.push_back(9);
Node n(v);

m[n] = 0;

return 0;
}
< /code>

Однако G ++ дает мне следующую ошибку: < /p>

In file included from /usr/include/c++/4.6/string:50:0,
from /usr/include/c++/4.6/bits/locale_classes.h:42,
from /usr/include/c++/4.6/bits/ios_base.h:43,
from /usr/include/c++/4.6/ios:43,
from /usr/include/c++/4.6/ostream:40,
from /usr/include/c++/4.6/iostream:40,
from 3sum.cpp:4:
/usr/include/c++/4.6/bits/stl_function.h: In member function ‘bool std::equal_to::operator()(const _Tp&, const _Tp&) const [with _Tp = Node]’:
/usr/include/c++/4.6/bits/hashtable_policy.h:768:48: instantiated from ‘bool std::__detail::_Hash_code_base::_M_compare(const _Key&, std::__detail::_Hash_code_base::_Hash_code_type, std::__detail::_Hash_node*) const [with _Key = Node, _Value = std::pair, _ExtractKey = std::_Select1st, _Equal = std::equal_to, _H1 = std::hash, _H2 = std::__detail::_Mod_range_hashing, std::__detail::_Hash_code_base::_Hash_code_type = long unsigned int]’
/usr/include/c++/4.6/bits/hashtable.h:897:2: instantiated from ‘std::_Hashtable::_Node* std::_Hashtable::_M_find_node(std::_Hashtable::_Node*, const key_type&, typename std::_Hashtable::_Hash_code_type) const [with _Key = Node, _Value = std::pair, _Allocator = std::allocator, _ExtractKey = std::_Select1st, _Equal = std::equal_to, _H1 = std::hash, _H2 = std::__detail::_Mod_range_hashing, _Hash = std::__detail::_Default_ranged_hash, _RehashPolicy = std::__detail::_Prime_rehash_policy, bool __cache_hash_code = false, bool __constant_iterators = false, bool __unique_keys = true, std::_Hashtable::_Node = std::__detail::_Hash_node, std::_Hashtable::key_type = Node, typename std::_Hashtable::_Hash_code_type = long unsigned int]’
/usr/include/c++/4.6/bits/hashtable_policy.h:546:53: instantiated from ‘std::__detail::_Map_base::mapped_type& std::__detail::_Map_base::operator[](const _Key&) [with _Key = Node, _Pair = std::pair, _Hashtable = std::_Hashtable, std::__detail::_Map_base::mapped_type = int]’
3sum.cpp:149:5: instantiated from here
/usr/include/c++/4.6/bits/stl_function.h:209:23: error: passing ‘const Node’ as ‘this’ argument of ‘bool Node::operator==(Node)’ discards qualifiers [-fpermissive]
make: *** [threeSum] Error 1
< /code>

Я думаю, мне нужен Tell C ++ Как хэш класс узел < /code>, однако я не совсем уверен, как это сделать. Как я могу выполнить эти задачи?

Подробнее здесь: https://stackoverflow.com/questions/170 ... as-the-key