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
1 type
2 node=record
3 l,r:longint;
4 end;
5 var n,l,i,ans:longint;
6 k:array[0..10001] of node;
7 function ma(a,b:longint):longint;
8 begin
9 if a>b then exit(a) else exit(b);
10 end;
11 procedure qs(t,w:longint);
12 var mid,l,r:longint;
13 tem:node;
14 begin
15 l:=t; r:=w; mid:=k[(l+r) shr 1].l;
16 repeat
17 begin
18 while k[l].l<mid do inc(l);
19 while k[r].l>mid do dec(r);
20 if l<=r then
21 begin
22 tem:=k[l];
23 k[l]:=k[r];
24 k[r]:=tem;
25 inc(l); dec(r);
26 end;
27 end;
28 until l>r;
29 if t<r then qs(t,r);
30 if l<w then qs(l,w);
31 end;
32 begin
33 readln(n,l);
34 for i:=1 to n do
35 readln(k[i].l,k[i].r);
36 qs(1,n);
37 for i:=1 to n do
38 begin
39 if k[i].l>=k[i].r then
40 begin
41 k[i+1].l:=ma(k[i+1].l,k[i].l);
42 continue;
43 end;
44 inc(ans,(k[i].r-k[i].l) div l);
45 if ((k[i].r-k[i].l) div l)*l<>k[i].r-k[i].l then
46 begin
47 inc(ans);
48 k[i+1].l:=ma(k[i+1].l,(((k[i].r-k[i].l) div l)+1)*l+k[i].l);
49 end;
50 end;
51 writeln(ans);
52 end.
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