#include <bits/stdc++.h>
using namespace std;
#define REP(i, j, k) for (int i = j; i < k; i++)
#define RREP(i, j, k) for (int i = j; i >= k; i--)
template<class T>
inline bool mxto(T &a, T b) {return a < b ? a = b, 1 : 0;}
template<class T>
inline bool mnto(T &a, T b) {return a > b ? a = b, 1 : 0;}
typedef long long ll;
#define FI first
#define SE second
#define MP make_pair
typedef pair<int, int> ii;
#define pb push_back
#define ALL(x) x.begin(), x.end()
typedef vector<int> vi;
typedef vector<ii> vii;
#ifndef DEBUG
#define cerr if (0) cerr
#endif
#define INF 1000000005
#define LINF 1000000000000000005ll
#define MAXN 10005
#define MOD 1000007
int n;
int a[MAXN];
int memo[2][MAXN][2];
int dp(int i, int j, bool same) {
if (i >= n) {
return 1;
}
if (memo[i & 1][j][same] != -1) {
return memo[i & 1][j][same];
}
int res = 0;
if (same) {
res += (ll) dp(i + 1, j, 0) * min(j, a[i] - 1) % MOD;
if (res >= MOD) {
res -= MOD;
}
if (a[i] <= j + 1) {
res += dp(i + 1, max(j, a[i]), 1);
if (res >= MOD) {
res -= MOD;
}
}
} else {
res += (ll) dp(i + 1, j, 0) * j % MOD;
if (res >= MOD) {
res -= MOD;
}
res += dp(i + 1, j + 1, 0);
if (res >= MOD) {
res -= MOD;
}
}
return memo[i & 1][j][same] = res;
}
int main() {
#ifndef DEBUG
ios::sync_with_stdio(0), cin.tie(0);
#endif
cin >> n;
REP (i, 0, n) {
cin >> a[i];
}
RREP (i, n - 1, 0) {
REP (j, 0, i + 1) {
REP (k, 0, 2) {
memo[i & 1][j][k] = -1;
dp(i, j, k);
}
}
}
cout << memo[0][0][1] << '\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
204 KB |
Output is correct |
4 |
Correct |
1 ms |
204 KB |
Output is correct |
5 |
Correct |
0 ms |
204 KB |
Output is correct |
6 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
0 ms |
204 KB |
Output is correct |
3 |
Correct |
0 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
332 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
204 KB |
Output is correct |
2 |
Correct |
1 ms |
204 KB |
Output is correct |
3 |
Correct |
1 ms |
204 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
5 ms |
384 KB |
Output is correct |
2 |
Correct |
4 ms |
204 KB |
Output is correct |
3 |
Correct |
5 ms |
336 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
14 ms |
332 KB |
Output is correct |
2 |
Correct |
14 ms |
332 KB |
Output is correct |
3 |
Correct |
13 ms |
348 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Execution timed out |
1086 ms |
460 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
357 ms |
408 KB |
Output is correct |
2 |
Correct |
335 ms |
428 KB |
Output is correct |
3 |
Correct |
323 ms |
432 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Execution timed out |
1085 ms |
460 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |