gistfile1.txt

$ g++ -g LRU.cpp 
In file included from LRU.cpp:2:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/ext/hash_map:212:5: warning: 
      Use of the header <ext/hash_map> is deprecated. Migrate to <unordered_map> [-W#warnings]
#   warning Use of the header <ext/hash_map> is deprecated.  Migrate to <unordered_map>
    ^
1 warning generated
$ lldb ./a.out 
(lldb) target create "./a.out"
Current executable set to './a.out' (x86_64).
(lldb) run
Process 27670 launched: './a.out' (x86_64)
Process 27670 stopped
* thread #1: tid = 0x8466ae, 0x000000010000392c a.out`LRUCache<int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::detach(this=0x00007fff5fbff310, node=0x0000000100104af0) + 28 at LRU.cpp:71, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x28)
    frame #0: 0x000000010000392c a.out`LRUCache<int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >::detach(this=0x00007fff5fbff310, node=0x0000000100104af0) + 28 at LRU.cpp:71
   68  	    
   69  	private:
   70  	    void detach(Node<K,T>* node){
-> 71  	        node->prev->next = node->next;
   72  	        node->next->prev = node->prev;
   73  	    }
   74  	    
(lldb) p node->prev
(Node<int, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > *) $0 = 0x0000000000000000