1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
#include <bits/stdc++.h>
#define f first
#define s second
using namespace std;
using ll = long long;
using ii = pair<int, int>;
const int MX = 3005, MOD = 1e9+7;
ll s[MX], t[MX], DP[2][MX][2];
int main() {
if (fopen("in", "r")) freopen("in", "r", stdin), freopen("out", "w", stdout);
ios_base::sync_with_stdio(0), cin.tie(0);
int N; cin >> N;
for (int i = 0; i < N; ++i) cin >> s[i];
for (int i = 0; i < N; ++i) cin >> t[i];
vector<ii> vc;
for (int i = 0; i < N; ++i) vc.emplace_back(s[i], 0);
for (int i = 0; i < N; ++i) vc.emplace_back(t[i], 1);
sort(begin(vc), end(vc));
DP[0][0][0] = 1;
for (int i = 0; i < 2*N; ++i) {
if (vc[i].s == 0) {
for (int j = 0; j <= N; ++j) {
(DP[1][j][1] += DP[0][j][0]) %= MOD;
(DP[1][j+1][0] += DP[0][j][0]) %= MOD;
(DP[1][j][1] += DP[0][j][1]) %= MOD;
(DP[1][j+1][1] += DP[0][j][1]) %= MOD;
}
}
else {
for (int j = 0; j <= N; ++j) {
(DP[1][j][0] += DP[0][j][0]) %= MOD;
if (j) (DP[1][j-1][0] += j*DP[0][j][0]) %= MOD;
if (j) (DP[1][j-1][1] += j*DP[0][j][1]) %= MOD;
}
}
memcpy(DP[0], DP[1], sizeof DP[1]);
memset(DP[1], 0, sizeof DP[1]);
}
cout << (DP[0][0][0]+DP[0][0][1])%MOD;
}
|
