P1689: [Usaco2005 Open] Muddy roads 泥泞的路

水题，模拟就行了，别忘了L>=r的时候直接更新下一个的L然后continue

 type
   node=record
     l,r:longint;
   end;
 var n,l,i,ans:longint;
 k:array[..] of node;
 function ma(a,b:longint):longint;
 begin
   if a>b then exit(a) else exit(b);
 end;
 procedure qs(t,w:longint);
 var mid,l,r:longint;
 tem:node;
 begin
   l:=t; r:=w; mid:=k[(l+r) shr ].l;
   repeat
     begin
       while k[l].l<mid do inc(l);
       while k[r].l>mid do dec(r);
       if l<=r then
         begin
           tem:=k[l];
           k[l]:=k[r];
           k[r]:=tem;
           inc(l); dec(r);
         end;
     end;
   until l>r;
   if t<r then qs(t,r);
   if l<w then qs(l,w);
 end;
 begin
   readln(n,l);
   for i:= to n do
     readln(k[i].l,k[i].r);
   qs(,n);
   for i:= to n do
     begin
       if k[i].l>=k[i].r then
         begin
           k[i+].l:=ma(k[i+].l,k[i].l);
           continue;
         end;
       inc(ans,(k[i].r-k[i].l) div l);
       if ((k[i].r-k[i].l) div l)*l<>k[i].r-k[i].l then
         begin
           inc(ans);
           k[i+].l:=ma(k[i+].l,(((k[i].r-k[i].l) div l)+)*l+k[i].l);
         end;
     end;
   writeln(ans);
 end.

(转载请注明出处：http://www.cnblogs.com/Kalenda/)