1506 Messenger _wikioi

This algorithm is simple, but timeout: var   n,m,i,x,y:longint;   f:array[1..1000,1..1000] of Boolean; Procedure Floyd; var   k,i,j:longint; Begin   for K:=1 to N does     for I:=1 to N does       for J:=1 to N do       &N Bsp F[I,J]:=F[I,J] or (f[i,k) and f[k,j]); End Begin   Fillchar (f,sizeof (f), false);   Read (n,m);   for I:=1 to M do     begin       read (x,y);       F[x,y]:=true;     END;   Floyd;   for I:=1 to n do     if f[i,i] then Writeln (' T ')     else write (' F '); End. The simple deep search still timed out: var   n,m,a,b,i,d:longint;   f:array[1..1000,1..1000] of Boolean;   used:array[1..1000] of Boolean;   Flag:boolean; Procedure Search (X:longint;var d:longint); var   k:longint; Begin   if (x=i) and (d>0) and (not flag) then     begin       writeln (' T ');       Flag:=true;       exit;   &NBsp End   for K:=1 to N does     if (F[x,k]) and (not used[k]) then       begin       & nbsp Used[k]:=true;         Inc. (d);         search (k,d);         Used[k]:=false; {Remove this sentence or timeout, only 8 points, do not backtrack}       end; End Begin   Fillchar (f,sizeof (f), false);   Read (n,m);   for I:=1 to M do     begin       read (A,B);       F[a,b]:=true;     END;   for I:=1 to n do     begin       Fillchar (used,sizeof (used), false);       Flag:=false;       d:=0;       Search (i,d);       If not flag then Writeln (' F ');     END; End. Weakly weak ground: Still use adjacent chain table to keep the edge ...