Compilare: user.cpp: In function ‘void solve()’: user.cpp:24:15: warning: array subscript has type ‘char’ [-Wchar-subscripts] alpha[s[0]]++; ^ user.cpp:33:32: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(!alpha[s[j]]) ^ user.cpp:36:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] alpha[s[j]]++; ^ user.cpp:39:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] alpha[s[j]]++; ^ user.cpp:50:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] alpha[s[i]]--; ^ user.cpp:51:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(!alpha[s[i]]) ^