Compilare: main.cpp: In function 'void add_string()': main.cpp:22:29: warning: array subscript has type 'char' [-Wchar-subscripts] if ( trie[i].link[it] == 0 ) { ^ main.cpp:23:28: warning: array subscript has type 'char' [-Wchar-subscripts] trie[i].link[it] = n; ^ main.cpp:26:28: warning: array subscript has type 'char' [-Wchar-subscripts] i = trie[i].link[it]; ^ main.cpp: In function 'void delete_string()': main.cpp:34:28: warning: array subscript has type 'char' [-Wchar-subscripts] i = trie[i].link[it]; ^ main.cpp: In function 'int string_appearances()': main.cpp:42:46: warning: array subscript has type 'char' [-Wchar-subscripts] while ( it != s.end() && trie[i].link[*it] != 0 ) { ^ main.cpp:43:29: warning: array subscript has type 'char' [-Wchar-subscripts] i = trie[i].link[*it]; ^ main.cpp: In function 'int longest_common_prefix()': main.cpp:53:51: warning: array subscript has type 'char' [-Wchar-subscripts] while ( it != s.end() && trie[trie[i].link[*it]].prefix > 0 ) { ^ main.cpp:54:29: warning: array subscript has type 'char' [-Wchar-subscripts] i = trie[i].link[*it]; ^