1996: [Hnoi2010]chorus 合唱队

 1 /**************************************************************
 2     Problem: 1996
 3     User: HansBug
 4     Language: Pascal
 5     Result: Accepted
 6     Time:108 ms
 7     Memory:8172 kb
 8 ****************************************************************/
 9  
10 const p=19650827;
11 var
12    i,j,k,l,m,n:longint;
13    c:array[0..10000] of longint;
14    a:array[0..1005,0..1005,1..2] of longint;
15 begin
16      readln(n);
17      for i:=1 to n do
18          begin
19               read(c[i]);
20               a[i,i,0]:=1;
21          end;
22      readln;
23      for i:=n-1 downto 1 do
24          for j:=i+1 to n do
25              begin
26                   a[i,j,0]:=0;a[i,j,1]:=0;
27                   if c[i]<c[i+1] then inc(a[i,j,0],a[i+1,j,0]);
28                   if c[i]<c[j] then inc(a[i,j,0],a[i+1,j,1]);
29                   if c[j]>c[i] then inc(a[i,j,1],a[i,j-1,0]);
30                   if c[j]>c[j-1] then inc(a[i,j,1],a[i,j-1,1]);
31                   a[i,j,0]:=a[i,j,0] mod p;
32                   a[i,j,1]:=a[i,j,1] mod p;
33              end;
34      writeln((a[1,n,1]+a[1,n,0]) mod p);
35      readln;
36 end.