#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MOD = 1e6 + 7;
int a[10005];
int DP[10005];
int mxs[10005];
/*int solve(int N, int K){
//you have N numbers left, and they can start anywhere from 1 - K.
if (DP[N][K] != 0) return DP[N][K];
if (N == 0) return 1;
else{
return DP[N][K] = (((long long) K)*solve(N - 1, K) + solve(N - 1, K + 1))%MOD;
}
}*/
int cnt = 10005;
void evolve(){
for (int i = 0; i < cnt - 1; i++){
DP[i] = ((long long) i)*DP[i] + DP[i + 1];
DP[i] %= MOD;
}
cnt--;
}
int main(){
int N; cin >> N;
for (int i = 0; i < N; i++){
cin >> a[i];
}
for (int i = 0; i < cnt; i++){
DP[i] = 1;
}
ll res = 1;
int mx = 1;
for (int i = 0; i < N; i++){
mxs[i] = mx;
mx = max(mx, a[i]);
}
for (int i = N - 1; i >= 0; i--){
//matches prefix of length i
res += ((ll) a[i] - 1)*DP[mxs[i]];
evolve();
res %= MOD;
}
cout << res << endl;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
488 KB |
Output is correct |
3 |
Correct |
2 ms |
600 KB |
Output is correct |
4 |
Correct |
2 ms |
600 KB |
Output is correct |
5 |
Correct |
2 ms |
604 KB |
Output is correct |
6 |
Correct |
2 ms |
612 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
660 KB |
Output is correct |
2 |
Correct |
2 ms |
700 KB |
Output is correct |
3 |
Correct |
2 ms |
704 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
2 ms |
708 KB |
Output is correct |
2 |
Correct |
2 ms |
712 KB |
Output is correct |
3 |
Correct |
2 ms |
848 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
4 ms |
848 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
6 ms |
848 KB |
Output is correct |
2 |
Correct |
4 ms |
848 KB |
Output is correct |
3 |
Correct |
4 ms |
848 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
12 ms |
848 KB |
Output is correct |
2 |
Correct |
12 ms |
848 KB |
Output is correct |
3 |
Correct |
13 ms |
848 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
30 ms |
848 KB |
Output is correct |
2 |
Correct |
23 ms |
848 KB |
Output is correct |
3 |
Correct |
23 ms |
848 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
144 ms |
952 KB |
Output isn't correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
80 ms |
952 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
133 ms |
1016 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |