1996: [Hnoi2010]chorus 合唱队 DP

#include <algorithm>
#include <cstring>
#include <cstdio>
#include <iostream>
using namespace std;
#define mod 19650827
#define maxn 1100
int save[maxn],n;
int dp[maxn][maxn][2];
int main()
{
memset(dp,0,sizeof(dp));
scanf("%d",&n);
for (int i=1;i<=n;i++)
{
scanf("%d",&save[i]);
dp[i][i][0]=1;
}
for(int i=n-1;i>=1;i--)
{
for(int j=i+1;j<=n;j++)
{
if(save[i]<save[i+1])
dp[i][j][0]+=dp[i+1][j][0];

if(save[i]<save[j])
dp[i][j][0]+=dp[i+1][j][1];

if(save[j]>save[i])
dp[i][j][1]+=dp[i][j-1][0];

if(save[j]>save[j-1])
dp[i][j][1]+=dp[i][j-1][1];

dp[i][j][0]%=mod;
dp[i][j][1]%=mod;
}
}
int ans=(dp[1]
[0]+dp[1]
[1])%mod;
printf("%d\n",ans);

return 0;
}