#include<bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
#define F first
#define S second
typedef long long ll;
typedef pair<int, int> pii;
const int N=505, M=1e9+7;
int n, m, a[N], b[N], dp[N][2*N], c[2*N][N], en[N][N], h[2*N][N];
vector<int>v;
int tav(int x, int p){
int res=1;
while(p){
if(p&1)
res=1LL*res*x%M;
x=1LL*x*x%M;
p>>=1;
}
return res;
}
void pre(){
en[0][0]=1;
for(int i=1;i<=n;++i){
en[i][0]=1;
for(int j=1;j<=i;++j){
en[i][j]=en[i-1][j]+en[i-1][j-1];
if(en[i][j]>=M)
en[i][j]-=M;
}
}
for(int i=0;i<m;++i){
int x=v[i+1]-v[i];
c[i][0]=1;
for(int j=1;j<=min(n, x);++j){
c[i][j]=1LL*c[i][j-1]*(x-j+1)%M;
c[i][j]=1LL*c[i][j]*tav(j, M-2)%M;
}
}
for(int i=0;i<m;++i){
h[i][1]=c[i][1];
for(int j=2;j<=min(n, v[i+1]-v[i]);++j){
ll z=0;
for(int k=0;k<=j-2;++k)
z+=1LL*en[j-2][k]*c[i][k+2]%M;
h[i][j]=z%M;
}
}
}
int main(){
cin>>n;
for(int i=1;i<=n;++i){
cin>>a[i]>>b[i];
v.push_back(a[i]);
v.push_back(++b[i]);
}
sort(all(v));
v.resize(int(unique(all(v))-v.begin()));
m=(int)v.size()-1;
pre();
for(int i=0;i<m;++i)
dp[0][i]=1;
for(int i=1;i<=n;++i){
ll x=dp[i-1][0];
if(a[i]<=v[0]){
int tt=0;
for(int j=i;j>=1;--j){
if(a[j]<=v[0])
x+=h[0][++tt];
}
}
dp[i][0]=x%M;
for(int j=1;j<m;++j){
x=dp[i-1][j]+dp[i][j-1];
x+=M-dp[i-1][j-1];
if(a[i]<=v[j] && b[i]>=v[j+1]){
int tt=0;
for(int k=i;k>=1;--k){
if(a[k]<=v[j] && b[k]>=v[j+1])
x+=1LL*h[j][++tt]*dp[k-1][j-1]%M;
}
}
dp[i][j]=x%M;
}
}
cout<<(dp[n][m-1]+M-1)%M<<'\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
163 ms |
7116 KB |
Output is correct |
2 |
Correct |
155 ms |
7120 KB |
Output is correct |
3 |
Correct |
154 ms |
7220 KB |
Output is correct |
4 |
Correct |
154 ms |
7204 KB |
Output is correct |
5 |
Correct |
156 ms |
7200 KB |
Output is correct |
6 |
Correct |
154 ms |
7116 KB |
Output is correct |
7 |
Correct |
158 ms |
7132 KB |
Output is correct |
8 |
Correct |
158 ms |
7204 KB |
Output is correct |
9 |
Correct |
159 ms |
7176 KB |
Output is correct |
10 |
Correct |
165 ms |
7112 KB |
Output is correct |
11 |
Correct |
152 ms |
7204 KB |
Output is correct |
12 |
Correct |
155 ms |
7160 KB |
Output is correct |
13 |
Correct |
154 ms |
7144 KB |
Output is correct |
14 |
Correct |
156 ms |
7320 KB |
Output is correct |
15 |
Correct |
175 ms |
7232 KB |
Output is correct |
16 |
Correct |
29 ms |
3908 KB |
Output is correct |
17 |
Correct |
32 ms |
3984 KB |
Output is correct |
18 |
Correct |
33 ms |
3920 KB |
Output is correct |
19 |
Correct |
31 ms |
4012 KB |
Output is correct |
20 |
Correct |
30 ms |
4004 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
163 ms |
7116 KB |
Output is correct |
2 |
Correct |
155 ms |
7120 KB |
Output is correct |
3 |
Correct |
154 ms |
7220 KB |
Output is correct |
4 |
Correct |
154 ms |
7204 KB |
Output is correct |
5 |
Correct |
156 ms |
7200 KB |
Output is correct |
6 |
Correct |
154 ms |
7116 KB |
Output is correct |
7 |
Correct |
158 ms |
7132 KB |
Output is correct |
8 |
Correct |
158 ms |
7204 KB |
Output is correct |
9 |
Correct |
159 ms |
7176 KB |
Output is correct |
10 |
Correct |
165 ms |
7112 KB |
Output is correct |
11 |
Correct |
152 ms |
7204 KB |
Output is correct |
12 |
Correct |
155 ms |
7160 KB |
Output is correct |
13 |
Correct |
154 ms |
7144 KB |
Output is correct |
14 |
Correct |
156 ms |
7320 KB |
Output is correct |
15 |
Correct |
175 ms |
7232 KB |
Output is correct |
16 |
Correct |
29 ms |
3908 KB |
Output is correct |
17 |
Correct |
32 ms |
3984 KB |
Output is correct |
18 |
Correct |
33 ms |
3920 KB |
Output is correct |
19 |
Correct |
31 ms |
4012 KB |
Output is correct |
20 |
Correct |
30 ms |
4004 KB |
Output is correct |
21 |
Incorrect |
104 ms |
6856 KB |
Output isn't correct |
22 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
6 ms |
1620 KB |
Output is correct |
2 |
Correct |
7 ms |
1720 KB |
Output is correct |
3 |
Correct |
7 ms |
1620 KB |
Output is correct |
4 |
Correct |
7 ms |
1620 KB |
Output is correct |
5 |
Correct |
7 ms |
1724 KB |
Output is correct |
6 |
Correct |
7 ms |
1716 KB |
Output is correct |
7 |
Correct |
7 ms |
1620 KB |
Output is correct |
8 |
Correct |
8 ms |
1620 KB |
Output is correct |
9 |
Correct |
7 ms |
1620 KB |
Output is correct |
10 |
Correct |
8 ms |
1748 KB |
Output is correct |
11 |
Correct |
8 ms |
1620 KB |
Output is correct |
12 |
Correct |
7 ms |
1620 KB |
Output is correct |
13 |
Correct |
7 ms |
1720 KB |
Output is correct |
14 |
Correct |
7 ms |
1620 KB |
Output is correct |
15 |
Correct |
7 ms |
1712 KB |
Output is correct |
16 |
Correct |
4 ms |
1364 KB |
Output is correct |
17 |
Correct |
4 ms |
1364 KB |
Output is correct |
18 |
Correct |
4 ms |
1364 KB |
Output is correct |
19 |
Correct |
4 ms |
1364 KB |
Output is correct |
20 |
Correct |
4 ms |
1236 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
163 ms |
7116 KB |
Output is correct |
2 |
Correct |
155 ms |
7120 KB |
Output is correct |
3 |
Correct |
154 ms |
7220 KB |
Output is correct |
4 |
Correct |
154 ms |
7204 KB |
Output is correct |
5 |
Correct |
156 ms |
7200 KB |
Output is correct |
6 |
Correct |
154 ms |
7116 KB |
Output is correct |
7 |
Correct |
158 ms |
7132 KB |
Output is correct |
8 |
Correct |
158 ms |
7204 KB |
Output is correct |
9 |
Correct |
159 ms |
7176 KB |
Output is correct |
10 |
Correct |
165 ms |
7112 KB |
Output is correct |
11 |
Correct |
152 ms |
7204 KB |
Output is correct |
12 |
Correct |
155 ms |
7160 KB |
Output is correct |
13 |
Correct |
154 ms |
7144 KB |
Output is correct |
14 |
Correct |
156 ms |
7320 KB |
Output is correct |
15 |
Correct |
175 ms |
7232 KB |
Output is correct |
16 |
Correct |
29 ms |
3908 KB |
Output is correct |
17 |
Correct |
32 ms |
3984 KB |
Output is correct |
18 |
Correct |
33 ms |
3920 KB |
Output is correct |
19 |
Correct |
31 ms |
4012 KB |
Output is correct |
20 |
Correct |
30 ms |
4004 KB |
Output is correct |
21 |
Incorrect |
104 ms |
6856 KB |
Output isn't correct |
22 |
Halted |
0 ms |
0 KB |
- |