/**
* author: Haunted_Cpp
**/
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC target("fma,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
template<typename T> ostream &operator << (ostream &os, const vector<T> &v) { os << '{'; string sep; for (const auto &x : v) os << sep << x, sep = ", "; return os << '}'; }
template<typename T, size_t size> ostream &operator << (ostream &os, const array<T, size> &arr) { os << '{'; string sep; for (const auto &x : arr) os << sep << x, sep = ", "; return os << '}'; }
template<typename A, typename B> ostream &operator << (ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
void debug_out() { cerr << endl; }
template<typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << ' ' << H; debug_out(T...); }
#ifdef LOCAL
#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#else
#define debug(...) 47
#endif
const int N = 1e4 + 5;
const int MOD = 1e6 + 7;
int dp[2][N][2];
int add(int a, int b) {
int res = a + b;
if (res >= MOD) res -= MOD;
return res;
}
int mult(int a, int b) {
long long res = 1LL * a * b;
if (res >= MOD) res %= MOD;
return res;
}
int main () {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int> arr(n);
for (int i = 0; i < n; i++) cin >> arr[i];
for (int i = 1; i < arr[0]; i++) {
dp[0][i][1] = 1;
}
dp[0][arr[0]][0] = 1;
for (int i = 1; i < n; i++) {
for (int j = 1; j <= n; j++) {
dp[i & 1][j][1] = add(dp[i & 1][j][1], dp[(i - 1) & 1][j - 1][1]);
dp[i & 1][j][1] = add(dp[i & 1][j][1], mult(dp[(i - 1) & 1][j][1], j));
if (j < arr[i]) {
dp[i & 1][j][1] = add(dp[i & 1][j][1], dp[(i - 1) & 1][j - 1][0]);
dp[i & 1][j][1] = add(dp[i & 1][j][1], mult(dp[(i - 1) & 1][j][0], j));
} else {
if (j == arr[i]) dp[i & 1][j][0] = add(dp[i & 1][j][0], dp[(i - 1) & 1][j - 1][0]);
dp[i & 1][j][0] = add(dp[i & 1][j][0], mult(dp[(i - 1) & 1][j][0], min(j, arr[i])));
}
}
for (int j = 1; j <= n; j++) dp[(i + 1) & 1][j][0] = dp[(i + 1) & 1][j][1] = 0;
}
int res = 0;
for (int i = 1; i <= n; i++) {
res = add(res, dp[(n - 1) & 1][i][0]);
res = add(res, dp[(n - 1) & 1][i][1]);
}
cout << res << '\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
0 ms |
384 KB |
Output is correct |
3 |
Correct |
0 ms |
384 KB |
Output is correct |
4 |
Correct |
1 ms |
384 KB |
Output is correct |
5 |
Correct |
1 ms |
384 KB |
Output is correct |
6 |
Correct |
0 ms |
384 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
384 KB |
Output is correct |
2 |
Correct |
0 ms |
384 KB |
Output is correct |
3 |
Correct |
1 ms |
384 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
0 ms |
384 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
0 ms |
384 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
0 ms |
384 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
2 ms |
384 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
7 ms |
384 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
639 ms |
584 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
154 ms |
384 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
665 ms |
576 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |