Compilare: main.cpp: In function 'int main()': main.cpp:21:26: warning: array subscript has type 'char' [-Wchar-subscripts] 21 | while( ch[dq.back()]>=ch[i] and last[ch[dq.back()]-'a']!=dq.back()){ | ~~~~~~~^~ main.cpp:21:56: warning: array subscript has type 'char' [-Wchar-subscripts] 21 | while( ch[dq.back()]>=ch[i] and last[ch[dq.back()]-'a']!=dq.back()){ | ~~~~~~~^~ main.cpp:22:26: warning: array subscript has type 'char' [-Wchar-subscripts] 22 | in[ch[dq.back()]-'a']=false; | ~~~~~~~^~ main.cpp:28:22: warning: array subscript has type 'char' [-Wchar-subscripts] 28 | in[ch[dq.back()]-'a']=true; | ~~~~~~~^~ main.cpp:31:26: warning: array subscript has type 'char' [-Wchar-subscripts] 31 | cout<<ch[dq.front()]; | ~~~~~~~~^~