bzoj1975

显然是类似k短路，直接不停增广即可

好久没写A*了，裸的A*可能会TLE

加点剪枝就卡过去了………

 type node=record
        po,next:longint;
        cost:double;
      end;
      point=record
        loc:longint;
        num:double;
      end;

 var e,ee:array[..] of node;
     d:array[..] of double;
     q:array[..] of longint;
     h:array[..] of point;
     p,pp:array[..] of longint;
     v:array[..] of boolean;
     ans,t,x,y,i,len,n,m:longint;
     z,te:double;

 procedure swap(var a,b:point);
   var c:point;
   begin
     c:=a;
     a:=b;
     b:=c;
   end;

 procedure add(x,y:longint; z:double);
   begin
     e[i].po:=y;
     e[i].next:=p[x];
     e[i].cost:=z;
     p[x]:=i;
   end;

 procedure eadd(x,y:longint; z:double);
   begin
     ee[i].po:=y;
     ee[i].next:=pp[x];
     ee[i].cost:=z;
     pp[x]:=i;
   end;

 procedure spfa;
   var f,r,i,x,y:longint;
   begin
     for i:= to n- do
       d[i]:=1e40;
     d[n]:=;
     f:=;
     r:=;
     q[]:=n;
     while f<=r do
     begin
       x:=q[f];
       v[x]:=false;
       i:=pp[x];
       while i<> do
       begin
         y:=ee[i].po;
         if d[y]>d[x]+ee[i].cost then
         begin
           d[y]:=d[x]+ee[i].cost;
           if not v[y] then
           begin
             v[y]:=true;
             inc(r);
             q[r]:=y;
           end;
         end;
         i:=ee[i].next;
       end;
       inc(f);
     end;
   end;

 procedure sift(i:longint);
   var j:longint;
   begin
     j:=i shl ;
     while j<=t do
     begin
       if (j<t) and (h[j].num>h[j+].num) then inc(j);
       if h[i].num>h[j].num then
       begin
         swap(h[i],h[j]);
         i:=j;
         j:=j shl ;
       end
       else break;
     end;
   end;

 procedure up(i:longint);
   var j:longint;
   begin
     j:=i shr ;
     while j> do
     begin
       if h[i].num<h[j].num then
       begin
         swap(h[i],h[j]);
         i:=j;
         j:=j shr ;
       end
       else break;
     end;
   end;

 procedure astar;
   var i,x,y:longint;
       dis:double;

   begin
     h[].loc:=;
     h[].num:=d[];
     t:=;
     while t> do
     begin
       x:=h[].loc;
       dis:=h[].num-d[x];
       swap(h[],h[t]);
       dec(t);
       sift();
       if x=n then
       begin
         if te<dis then break
         else begin
           inc(ans);
           te:=te-dis;
         end;
       //  writeln(te,' ',dis);
       end;
       i:=p[x];
       while i<> do
       begin
         y:=e[i].po;
         if dis+e[i].cost+d[y]<=te then
         begin
           inc(t);
           h[t].loc:=y;
           h[t].num:=dis+e[i].cost+d[y];
           up(t);
         end;
         i:=e[i].next;
       end;
     end;
   end;

 begin
   readln(n,m,te);
   for i:= to m do
   begin
     readln(x,y,z);
     add(x,y,z);
     eadd(y,x,z);
   end;
   spfa;
   astar;
   writeln(ans);
 end.