Compilare: user.cpp: In function ‘int main()’: user.cpp:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<ss.length(); i++) a[ss[i]]++ , b[ss[i]]++; ~^~~~~~~~~~~~ user.cpp:27:46: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i=0; i<ss.length(); i++) a[ss[i]]++ , b[ss[i]]++; ^ user.cpp:27:59: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i=0; i<ss.length(); i++) a[ss[i]]++ , b[ss[i]]++; ^ user.cpp:30:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (b[s[i]]) b[s[i]]--; ^ user.cpp:30:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (b[s[i]]) b[s[i]]--; ^ user.cpp:39:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (nr < dp[1] && st < s.length()){ ~~~^~~~~~~~~~~~ user.cpp:41:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (dr + 1 < s.length() && dp[st] - dp[dr+1] <= 1) dr++; ~~~~~~~^~~~~~~~~~~~ user.cpp:42:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (dr != s.length() - 1) dr--; ~~~^~~~~~~~~~~~~~~~~ user.cpp:46:48: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (int i=st; i<=dr; i++) cnt[s[i]]++; ^ user.cpp:50:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (!a[s[st]] || !b[s[st]]) cnt[s[st]]--, st++; ^ user.cpp:50:42: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (!a[s[st]] || !b[s[st]]) cnt[s[st]]--, st++; ^ user.cpp:50:54: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (!a[s[st]] || !b[s[st]]) cnt[s[st]]--, st++; ^ user.cpp:51:81: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if (S.empty() || s[st] >= S.top()) S.push(s[st]), cnt[s[st]]--, b[s[st]]--, last = st, st++; ^ user.cpp:51:93: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if (S.empty() || s[st] >= S.top()) S.push(s[st]), cnt[s[st]]--, b[s[st]]--, last = st, st++; ^ user.cpp:52:37: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if (cnt[S.top()] > b[S.top()]) b[S.top()]++, S.pop(); ^ user.cpp:52:50: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if (cnt[S.top()] > b[S.top()]) b[S.top()]++, S.pop(); ^ user.cpp:52:62: warning: array subscript has type ‘char’ [-Wchar-subscripts]