Compilare: user.cpp: In function ‘bool ok(int)’: user.cpp:11:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] int poz=a[s[0]][0],step,j,y=0; ^ user.cpp:14:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(y+nr-1<a[s[i-1]].size()) ^ user.cpp:14:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(y+nr-1<a[s[i-1]].size()) ~~~~~~^~~~~~~~~~~~~~~~~ user.cpp:16:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] poz=a[s[i-1]][y+nr-1]; ^ user.cpp:20:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(step<a[s[i]].size()-1)step<<=1; ^ user.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(step<a[s[i]].size()-1)step<<=1; ~~~~^~~~~~~~~~~~~~~~~ user.cpp:23:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(j+step<=a[s[i]].size()-1 && a[s[i]][j+step]<=poz) ^ user.cpp:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j+step<=a[s[i]].size()-1 && a[s[i]][j+step]<=poz) ~~~~~~^~~~~~~~~~~~~~~~~~ user.cpp:23:50: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(j+step<=a[s[i]].size()-1 && a[s[i]][j+step]<=poz) ^ user.cpp:28:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(a[s[i]][j]<=poz) ^ user.cpp:34:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(y+nr-1>=a[s[m-1]].size()) ^ user.cpp:34:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(y+nr-1>=a[s[m-1]].size()) ~~~~~~^~~~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:64:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] a[x].push_back(i); ^ user.cpp: In function ‘int solve()’: user.cpp:56:12: warning: ‘sol’ may be used uninitialized in this function [-Wmaybe-uninitialized] return sol; ^~~