|
|
back to boardWhy I got Wang Answer?????? Posted by qwt 11 Mar 2002 18:05 const maxn=10000; var start,n,i,j,k,m:integer; a:array[0..maxn] of integer; procedure over; begin writeln('NO'); halt; end; begin fillchar(a,sizeof(A),0); read(n,m); for i:=1 to m do begin read(j); inc(a[j]); end; for i:=1 to n do if a[i]>2 then over; if (a[0]>1)or(a[n]>1) then over; repeat start:=-1; if a[0]=1 then start:=0 else for i:=1 to n-1 do if a[i]=2 then begin start:=i;break;end; for i:=start+1 to n-1 do if a[i]=0 then begin a[start]:=0; break; end else if a[i]>=2 then over; if (start=n-1)and(a[n]>0) then over; a[start]:=0; until (start=n-1)or(start=-1); writeln('YES'); end. |
|
|