#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define fr first
#define sc second
#define ARRS ((ll)(2e6+500))
#define MAX ((ll)(1e6+100))
#define MOD ((ll)1e9+7)
#define mi(a,b) a=min((a),(b))
ll n,m,k,p,l,r,q;
ll a[ARRS];
int f[1005][1005][2];
ll slv(ll i,ll c,ll e=0){
if(i==n)return 1;
if(f[i][c][e])return f[i][c][e]-1;
if(e){
f[i][c][e]=c*slv(i+1,c,e)+slv(i+1,c+1,e)+1;
return f[i][c][e]-1;
}
else {
ll pas=0;
if(a[i]==c+1){
pas+=c*slv(i+1,c,1);
pas+=slv(i+1,c+1,0);
}
else {
pas+=(a[i]-1)*slv(i+1,c,1);
pas+=slv(i+1,c,0);
}
pas%=MOD;
f[i][c][e]=pas+1;
return pas;
}
}
int main(){
#ifdef KHOKHO
freopen("in.in","r",stdin);
freopen("out.out","w",stdout);
#endif
cin>>n;
for(int i=0; i<n; i++)cin>>a[i];
cout<<slv(0,0,0);
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
376 KB |
Output is correct |
2 |
Correct |
2 ms |
452 KB |
Output is correct |
3 |
Correct |
3 ms |
452 KB |
Output is correct |
4 |
Correct |
2 ms |
452 KB |
Output is correct |
5 |
Correct |
3 ms |
452 KB |
Output is correct |
6 |
Correct |
2 ms |
632 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
632 KB |
Output is correct |
2 |
Correct |
3 ms |
632 KB |
Output is correct |
3 |
Correct |
3 ms |
632 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
3 ms |
632 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
3 ms |
952 KB |
Output isn't correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
3 ms |
952 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
8 ms |
3560 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
24 ms |
7648 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
11 ms |
7648 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
10 ms |
7648 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
9 ms |
7648 KB |
Execution killed with signal 11 (could be triggered by violating memory limits) |
2 |
Halted |
0 ms |
0 KB |
- |