#include<bits/stdc++.h>
#define maxn 1005
#define mod 1000007
#define ll long long
using namespace std;
int n;
int a[maxn];
ll dp[maxn][maxn];
int g[maxn];
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin>>n;
for(int i=1;i<=n;i++)cin>>a[i];
g[1]=1;
for(int i=2;i<=n;i++)g[i]=max(g[i-1],a[i]);
for(int d=1;d<n;d++)
{
for(int k=1;k+d<=n;k++)
{
if(d==1)dp[d][k]=k+1;
else
{
dp[d][k]=dp[d-1][k+1]+k*dp[d-1][k];
dp[d][k]%=mod;
}
}
}
/*for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
cout<<dp[i][j]<<" ";
}
cout<<endl;
}*/
long long ans=0;
for(int i=2;i<=n;i++)
{
ll br;
if(i==n)
{
br=1;
}
else if(g[i]==g[i-1])
{
br=dp[n-i][g[i]];
}
else
{
br=dp[n-i][g[i]-1];
}
ans+=(g[i]-1)*br;
ans%=mod;
}
cout<<(ans+1)%mod<<endl;
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
376 KB |
Output is correct |
3 |
Incorrect |
2 ms |
376 KB |
Output isn't correct |
4 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
504 KB |
Output is correct |
2 |
Incorrect |
2 ms |
376 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
376 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
760 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
760 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
4 ms |
3324 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
9 ms |
7288 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
9 ms |
7288 KB |
Output isn't correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
376 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
1 ms |
504 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |