题目说是拓扑图，所以提示是DP，之前跟FK学到逆拓扑这次用了。需要注意的是题目要求一条完整的路，所以初始化为-oo。因为TUOPU写萎了，WA了2次。之前FK那个题因为是无向图，而且是树，而且起点还是root，所以可以直接BFS就得到拓扑序，这个题不行。

Codeuses math;const maxn=100000;      maxm=11000000;var a,Q,Adjlist,d:array[1..maxn] of longint;    f:array[1..maxn] of int64;    vis:array[1..maxn] of boolean;    v,next:array[1..maxm] of longint;    count,x,y,i,h,t,tot,n,m:longint;    ans:int64;procedure build(x,y:longint);          begin          inc(tot);          v[tot]:=y;          next[tot]:=Adjlist[x];          Adjlist[x]:=tot;          end;procedure TUOPUSort;          var i:longint;          begin          while h
     
      0 do begin              dec(d[v[i]]);              if(not vis[v[i]])and(d[v[i]]=0)                then begin                     inc(t);Q[t]:=v[i];                     vis[v[i]]:=true;                     end;              i:=next[i];end;end;          end;procedure calc;          var i,u:longint;          begin          for h:=t downto 1 do            begin            i:=Adjlist[Q[h]];            if i=0 then f[Q[h]]:=A[Q[h]]                   else f[Q[h]]:=$8fffffffffffffff;            while i<>0 do begin              f[Q[h]]:=max(f[v[i]]+A[Q[h]],f[Q[h]]);              i:=next[i];end;            end;          end;beginreadln(n,m);ans:=$8fffffffffffffff;h:=0;t:=0;for i:=1 to n do readln(a[i]);for i:=1 to m do  begin  readln(x,y);  build(x,y);  inc(d[y]);  end;for i:=1 to n do  if(d[i]=0)    then begin         inc(t);         Q[t]:=i;         vis[i]:=true;         end;count:=t;TUOPUSort;calc;for i:=1 to count do  ans:=max(f[Q[i]],ans);writeln(ans);end.