#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
const ll mod=1e9+7,N=1e3+5;
ll binpow(ll a,ll b){
ll res=1;
while(b){
if(b&1){
res=res*a%mod;
}
a=a*a%mod;
b=b>>1;
}
return res;
}
ll inv(ll a){
return binpow(a,mod-2);
}
ll fact[N],invfact[N];
void init(){
fact[0]=1;
for(ll i=1;i<N;i++){
fact[i]=fact[i-1]*i%mod;
}
invfact[N-1]=inv(fact[N-1]);
for(ll i=N-1;i>=1;i--){
invfact[i-1]=invfact[i]*i%mod;
}
}
ll nCk(ll n,ll k){
if(k>n||k<0) return 0ll;
ll res=1;
for(ll i=n-k+1;i<=n;i++) res=res*i%mod;
res=res*invfact[k]%mod;
return res;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
init();
ll n;
cin>>n;
ll a[n+5],b[n+5];
set<ll>s;
for(ll i=1;i<=n;i++){
cin>>a[i]>>b[i];
s.insert(a[i]);
s.insert(b[i]+1);
}
ll cur=0;
ll l[2*n+5];
for(auto x:s){
cur++;
l[cur]=x;
}
ll dp[2*n+5][n+5],sum[2*n+5][n+5];
memset(sum,0,sizeof sum);
ll ans=0;
for(ll i=1;i<=n;i++){
ll tot=1;
memset(dp,0,sizeof dp);
for(ll j=1;j<cur;j++){//l[j] l[j+1]-1
if(b[i]>=l[j]&&a[i]<l[j+1]){
dp[j][1]=tot;
for(ll k=2;k<=n;k++){
dp[j][k]=sum[j][k-1];
}
}
for(ll k=1;k<=n;k++){
tot+=sum[j][k]*nCk(l[j+1]-l[j],k)%mod;
tot%=mod;
}
for(ll k=1;k<=n;k++){
sum[j][k]+=dp[j][k];
sum[j][k]%=mod;
}
}
}
for(ll j=1;j<cur;j++){
for(ll k=1;k<=n;k++){
ans+=sum[j][k]*nCk(l[j+1]-l[j],k)%mod;
ans%=mod;
}
}
cout<<ans;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
2035 ms |
8284 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
2035 ms |
8284 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
365 ms |
788 KB |
Output is correct |
2 |
Correct |
360 ms |
604 KB |
Output is correct |
3 |
Correct |
362 ms |
600 KB |
Output is correct |
4 |
Correct |
361 ms |
600 KB |
Output is correct |
5 |
Correct |
361 ms |
600 KB |
Output is correct |
6 |
Correct |
364 ms |
600 KB |
Output is correct |
7 |
Correct |
362 ms |
604 KB |
Output is correct |
8 |
Correct |
361 ms |
792 KB |
Output is correct |
9 |
Correct |
361 ms |
788 KB |
Output is correct |
10 |
Correct |
363 ms |
788 KB |
Output is correct |
11 |
Correct |
363 ms |
856 KB |
Output is correct |
12 |
Correct |
362 ms |
792 KB |
Output is correct |
13 |
Correct |
367 ms |
784 KB |
Output is correct |
14 |
Correct |
364 ms |
788 KB |
Output is correct |
15 |
Correct |
364 ms |
784 KB |
Output is correct |
16 |
Correct |
159 ms |
788 KB |
Output is correct |
17 |
Correct |
158 ms |
600 KB |
Output is correct |
18 |
Correct |
159 ms |
796 KB |
Output is correct |
19 |
Correct |
158 ms |
604 KB |
Output is correct |
20 |
Correct |
163 ms |
784 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Execution timed out |
2035 ms |
8284 KB |
Time limit exceeded |
2 |
Halted |
0 ms |
0 KB |
- |