P3205 [HNOI2010]合唱队

#include<bits/stdc++.h>
using namespace std;
const int n=1010;
int h[n];
int N;
int f[n][n][2];

int main(){
    scanf("%d",&N);
    for(int i=1;i<=N;i++){
        scanf("%d",&h[i]);
    }
    for(int i=1;i<=N;i++){
        f[i][i][0]=1;
    }
    for(int l=1;l<=N;l++){
        for(int i=1;i+l<=N;i++){
            int j=i+l;
            if(h[i]<h[i+1])f[i][j][0]+=f[i+1][j][0];
            if(h[i]<h[j])f[i][j][0]+=f[i+1][j][1];
            if(h[j]>h[i])f[i][j][1]+=f[i][j-1][0];
            if(h[j]>h[j-1])f[i][j][1]+=f[i][j-1][1];
            f[i][j][0]%=19650827;
            f[i][j][1]%=19650827;
        }
    }
    printf("%d\n",(f[1][N][0]+f[1][N][1])%19650827);
    return 0;
}

https://www.cnblogs.com/Liuz8848/p/11719556.html