#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
#define debug(...) void(23)
#endif
template<typename T>
T power(T a, i64 b) {
T res = 1;
while(b) {
if(b & 1) {
res *= a;
}
a *= a;
b >>= 1;
}
return res;
}
constexpr int md = int(1E6) + 7;
struct MInt {
int val;
MInt() : val(0) {}
template<typename T>
MInt(T v) {
if(-md <= v && v < md) {
val = v;
} else {
val = v % md;
}
if(val < 0) {
val += md;
}
}
int operator() () { return val; }
MInt operator+= (MInt rhs) {
if((val += rhs.val) >= md) {
val -= md;
}
return *this;
}
MInt operator-= (MInt rhs) {
if((val -= rhs.val) < 0) {
val += md;
}
return *this;
}
MInt operator*= (MInt rhs) {
val = (int)(1LL * val * rhs.val % md);
return *this;
}
MInt inv() {
return power(*this, md - 2);
}
MInt operator/= (MInt rhs) {
return *this *= rhs.inv();
}
bool operator== (MInt rhs) {
return val == rhs.val;
}
bool operator!= (MInt rhs) {
return val != rhs.val;
}
};
MInt operator+ (MInt lhs, MInt rhs) {
return lhs += rhs;
}
MInt operator- (MInt lhs, MInt rhs) {
return lhs -= rhs;
}
MInt operator* (MInt lhs, MInt rhs) {
return lhs *= rhs;
}
MInt operator/ (MInt lhs, MInt rhs) {
return lhs /= rhs;
}
std::ostream& operator<< (std::ostream& os, MInt v) {
return os << v();
}
std::string to_string(MInt x) {
return to_string(x());
}
using Z = MInt;
constexpr int max_N = int(1E4) + 5;
int N, A[max_N];
Z dp[2][2][max_N];
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
std::cin >> N;
for (int i = 0; i < N; ++i) {
std::cin >> A[i];
}
dp[0][0][0] = 1;
for (int i = 0; i < N; ++i) {
for (int j = 0; j < max_N; ++j) {
dp[1][0][j] = dp[1][1][j] = 0;
}
for (int j = 0; j <= N; ++j) {
if (dp[0][0][j] != 0) {
dp[1][1][j] += dp[0][0][j] * std::max(0, std::min(A[i] - 1, j));
if (j + 1 >= A[i]) {
dp[1][0][std::max(j, A[i])] += dp[0][0][j];
}
}
if (dp[0][1][j] != 0) {
dp[1][1][j] += dp[0][1][j] * j;
dp[1][1][j + 1] += dp[0][1][j];
}
}
std::swap(dp[0], dp[1]);
}
Z ans = 0;
for (int i = 0; i <= N; ++i) {
ans += dp[0][0][i] + dp[0][1][i];
}
std::cout << ans << '\n';
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
592 KB |
Output is correct |
2 |
Correct |
1 ms |
592 KB |
Output is correct |
3 |
Correct |
1 ms |
592 KB |
Output is correct |
4 |
Correct |
1 ms |
592 KB |
Output is correct |
5 |
Correct |
1 ms |
760 KB |
Output is correct |
6 |
Correct |
1 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
592 KB |
Output is correct |
2 |
Correct |
1 ms |
592 KB |
Output is correct |
3 |
Correct |
1 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
592 KB |
Output is correct |
2 |
Correct |
2 ms |
592 KB |
Output is correct |
3 |
Correct |
1 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
3 ms |
764 KB |
Output is correct |
2 |
Correct |
3 ms |
592 KB |
Output is correct |
3 |
Correct |
3 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
9 ms |
620 KB |
Output is correct |
2 |
Correct |
9 ms |
760 KB |
Output is correct |
3 |
Correct |
9 ms |
604 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
22 ms |
592 KB |
Output is correct |
2 |
Correct |
18 ms |
592 KB |
Output is correct |
3 |
Correct |
18 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
322 ms |
592 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
120 ms |
592 KB |
Output is correct |
2 |
Correct |
127 ms |
840 KB |
Output is correct |
3 |
Correct |
119 ms |
764 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
331 ms |
592 KB |
Output is correct |
2 |
Correct |
336 ms |
592 KB |
Output is correct |
3 |
Correct |
322 ms |
592 KB |
Output is correct |