#include <bits/stdc++.h>
#define ll long long
const ll MOD=1000000007;
using namespace std;
ll n,k;
ll l[505],r[505],dp[505][1005],val[1005],cnt[505][1005],c[505][1005],sum[505][1005],len[1005];
unordered_map<ll,ll>um;
set<ll>s;
ll power(ll x,ll y){
ll res=1;
while(y){
if(y&1){
res=res*x;
if(res>=MOD) res%=MOD;
}
y>>=1;
x=x*x;
if(x>=MOD) x%=MOD;
}
return res;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n;
for(ll i=1;i<=n;i++){
cin >> l[i] >> r[i];
s.insert(l[i]);
s.insert(r[i]+1);
}
for(auto i=s.begin();i!=s.end();++i){
um[*i]=++k;
val[k]=*i;
if(k>1) len[k-1]=val[k]-val[k-1];
}
for(ll i=1;i<k;i++){
c[i][0]=1;
for(ll j=1;j<=n;j++){
if(j>len[i]) sum[i][j]=sum[i][j-1];
else{
c[i][j]=c[i][j-1]*(n+1-j);
if(c[i][j]>=MOD) c[i][j]%=MOD;
c[i][j]*=power(i,MOD-2);
if(c[i][j]>=MOD) c[i][j]%=MOD;
sum[i][j]=sum[i][j-1]+c[i][j];
if(sum[i][j]>=MOD) sum[i][j]%=MOD;
}
}
}
for(ll i=1;i<=n;i++){
for(ll j=1;j<k;j++){
if(l[i]<=val[j] && val[j]<r[i]){
cnt[i][j]=cnt[i-1][j]+1;
}
else cnt[i][j]=cnt[i-1][j];
}
}
for(ll i=0;i<=n;i++) dp[i][0]=1;
for(ll i=0;i<=n;i++){
for(ll j=1;j<k;j++){
dp[i][j]+=dp[i][j-1];
if(dp[i][j]>=MOD) dp[i][j]%=MOD;
for(ll t=0;t<i;t++){
if(val[j+1]<=l[t+1] || r[t+1]<val[j]) continue;
ll p=cnt[i][j]-cnt[t][j];
dp[i][j]+=(dp[t][j-1]*sum[j][p]);
if(dp[i][j]>=MOD) dp[i][j]%=MOD;
}
}
}
cout << dp[n][k-1];
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
313 ms |
16196 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
313 ms |
16196 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
9 ms |
3260 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
313 ms |
16196 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |