1996: [Hnoi2010]chorus 合唱队
Time Limit: 4 Sec Memory Limit: 64 MBSubmit: 1057 Solved: 681
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Description
![](http://www.lydsy.com/JudgeOnline/images/1996_1.jpg)
Input
![](http://www.lydsy.com/JudgeOnline/images/1996_2.jpg)
Output
![](http://www.lydsy.com/JudgeOnline/images/1996_3.jpg)
Sample Input
4
1701 1702 1703 1704
1701 1702 1703 1704
Sample Output
8
HINT
Source
题解:萌萌哒DP题,其实和我一开始想的暴力方法很接近,基本上就是记忆化暴力,然后转变为循环形式(HansBug:无后效性这玩意就是爽^_^),然后就只管AC啦
(PS:不过话说第一遍的记忆化暴力WA掉了是What Ghost???)
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.