#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<limits.h>
#include<numeric> //gcd(a,b)
#include<cmath>
#include<set>
#include<cassert>
#include<algorithm>
#include<bitset>
#include<stack>
//#include "aliens.h"
using namespace std;
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define pppiiii pair<pii,pii>
#define ppii pair<int,pii>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define pb push_back
//#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#define int int64_t
const int mxn=1000+10,minf=-1e18,mod=1e9+7,inf=1e18,lg=30;
int dp[mxn+10][mxn+10],ncr[mxn+10][mxn+10],sum[mxn+10][mxn+10];
int ncr2[mxn+10][mxn+10];
int choose[mxn+10][mxn+10];
int fac[mxn+10];
int inv(int x){
int ex=mod-2,ans=1;
while(ex){
if(ex&1)ans=(ans*x)%mod;
x=(x*x)%mod;
ex>>=1;
}
return ans;
}
int32_t main(){
fastio
int n;cin>>n;
vector<pii>v(n+1);
vector<int>com;
for(int i=1;i<=n;i++)cin>>v[i].f>>v[i].s,v[i].f--;
for(int i=1;i<=n;i++)com.pb(v[i].f),com.pb(v[i].s);
sort(all(com));
com.erase(unique(all(com)),com.end());
/*
for(auto i:com)cout<<i<<" ";
cout<<'\n'<<'\n';*/
/*
ncr i,j->(i,j+1)
x=(x*(len-j+1))*inv(j)
*/
ncr[0][0]=1;
for(int i=1;i<=n;i++)for(int j=0;j<=n;j++){
if(j)ncr[i][j]=(ncr[i-1][j]+ncr[i-1][j-1])%mod;
else ncr[i][j]=ncr[i-1][j];
}
//for(int i=0;i<=n;i++)ncr[0][i]=1;
for(int i=1;i<com.size();i++){
int len=com[i]-com[i-1];
ncr2[i][1]=len;
for(int j=2;j<=n;j++)ncr2[i][j]=((ncr2[i][j-1]*(len-j+1))%mod*inv(j))%mod;
}
for(int i=1;i<com.size();i++){
choose[i][1]=ncr2[i][1];
for(int j=2;j<=n;j++){
int sum=0;
//ith segment have j
//need to fix 2
//k=use so use 2->min(j,len)
//
//cout<<i<<" "<<j<<"G\n";
for(int k=2;k<=j;k++){
sum=(sum+(ncr2[i][k]*(ncr[j-2][k-2])%mod))%mod;
//cout<<ncr2[i][k]<<" "<<ncr[j-2][k]<<"L\n";
//cout<<sum<<'\n';
}
choose[i][j]=sum;
}
}
//cout<<choose[2][2]<<"LL\n";
for(int i=0;i<=2*n;i++)sum[0][i]=1;
for(int i=0;i<=2*n;i++)sum[i][0]=1;
for(int i=1;i<=n;i++){
for(int j=1;j<com.size();j++){
if(com[j]>v[i].f&&com[j]<=v[i].s){
if(choose[j][1]==1)dp[i][j]=sum[i-1][j-1];
else{
int cnt=0;
for(int back=i;back>=1;back--){
if(com[j]>v[back].f&&com[j]<=v[back].s){
cnt++;
//cout<<i<<" "<<j<<" "<<back<<" "<<sum[back-1][j-1]<<" "<<choose[j][cnt]<<' '<<cnt<<'\n';
dp[i][j]=(dp[i][j]+(sum[back-1][j-1]*choose[j][cnt])%mod)%mod;
}
}
}
}
sum[i][j]=((dp[i][j]+(sum[i-1][j]+sum[i][j-1])%mod)%mod-sum[i-1][j-1]+mod)%mod;
}
}
/*
for(int i=1;i<=n;i++){
for(int j=0;j<com.size();j++)cout<<dp[i][j]<<" ";
cout<<'\n';
}*/
cout<<sum[n][com.size()-1]-1;
}
/*
dp[i][j]->last pick at i and on segment j or less
dp[i][j]->back[j-1]*(len cnt)
we want to compute (len ,cnt)
=the num of ways to assign each cnt to each val in len
if we know len cnt
then num of ways to assign cnt to len-> ncr(len,cnt)
we also need to fix 2
*/
Compilation message
boat.cpp: In function 'int32_t main()':
boat.cpp:70:15: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
70 | for(int i=1;i<com.size();i++){
| ~^~~~~~~~~~~
boat.cpp:75:15: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
75 | for(int i=1;i<com.size();i++){
| ~^~~~~~~~~~~
boat.cpp:96:16: warning: comparison of integer expressions of different signedness: 'int64_t' {aka 'long int'} and 'std::vector<long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
96 | for(int j=1;j<com.size();j++){
| ~^~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
540 ms |
30032 KB |
Output is correct |
2 |
Correct |
550 ms |
29832 KB |
Output is correct |
3 |
Correct |
543 ms |
30864 KB |
Output is correct |
4 |
Correct |
540 ms |
30036 KB |
Output is correct |
5 |
Correct |
533 ms |
29896 KB |
Output is correct |
6 |
Correct |
534 ms |
33184 KB |
Output is correct |
7 |
Correct |
544 ms |
29896 KB |
Output is correct |
8 |
Correct |
533 ms |
30072 KB |
Output is correct |
9 |
Correct |
533 ms |
30036 KB |
Output is correct |
10 |
Correct |
532 ms |
30212 KB |
Output is correct |
11 |
Correct |
538 ms |
30084 KB |
Output is correct |
12 |
Correct |
535 ms |
30116 KB |
Output is correct |
13 |
Correct |
532 ms |
30208 KB |
Output is correct |
14 |
Correct |
533 ms |
32968 KB |
Output is correct |
15 |
Correct |
534 ms |
30064 KB |
Output is correct |
16 |
Correct |
98 ms |
21916 KB |
Output is correct |
17 |
Correct |
103 ms |
22040 KB |
Output is correct |
18 |
Correct |
100 ms |
21904 KB |
Output is correct |
19 |
Correct |
104 ms |
21908 KB |
Output is correct |
20 |
Correct |
101 ms |
21920 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
540 ms |
30032 KB |
Output is correct |
2 |
Correct |
550 ms |
29832 KB |
Output is correct |
3 |
Correct |
543 ms |
30864 KB |
Output is correct |
4 |
Correct |
540 ms |
30036 KB |
Output is correct |
5 |
Correct |
533 ms |
29896 KB |
Output is correct |
6 |
Correct |
534 ms |
33184 KB |
Output is correct |
7 |
Correct |
544 ms |
29896 KB |
Output is correct |
8 |
Correct |
533 ms |
30072 KB |
Output is correct |
9 |
Correct |
533 ms |
30036 KB |
Output is correct |
10 |
Correct |
532 ms |
30212 KB |
Output is correct |
11 |
Correct |
538 ms |
30084 KB |
Output is correct |
12 |
Correct |
535 ms |
30116 KB |
Output is correct |
13 |
Correct |
532 ms |
30208 KB |
Output is correct |
14 |
Correct |
533 ms |
32968 KB |
Output is correct |
15 |
Correct |
534 ms |
30064 KB |
Output is correct |
16 |
Correct |
98 ms |
21916 KB |
Output is correct |
17 |
Correct |
103 ms |
22040 KB |
Output is correct |
18 |
Correct |
100 ms |
21904 KB |
Output is correct |
19 |
Correct |
104 ms |
21908 KB |
Output is correct |
20 |
Correct |
101 ms |
21920 KB |
Output is correct |
21 |
Correct |
565 ms |
30956 KB |
Output is correct |
22 |
Correct |
566 ms |
31000 KB |
Output is correct |
23 |
Correct |
551 ms |
31056 KB |
Output is correct |
24 |
Correct |
564 ms |
31124 KB |
Output is correct |
25 |
Correct |
568 ms |
32300 KB |
Output is correct |
26 |
Correct |
598 ms |
30676 KB |
Output is correct |
27 |
Correct |
602 ms |
31808 KB |
Output is correct |
28 |
Correct |
631 ms |
31668 KB |
Output is correct |
29 |
Correct |
598 ms |
31644 KB |
Output is correct |
30 |
Correct |
530 ms |
30032 KB |
Output is correct |
31 |
Correct |
546 ms |
29932 KB |
Output is correct |
32 |
Correct |
540 ms |
30964 KB |
Output is correct |
33 |
Correct |
543 ms |
29864 KB |
Output is correct |
34 |
Correct |
538 ms |
30072 KB |
Output is correct |
35 |
Correct |
539 ms |
31400 KB |
Output is correct |
36 |
Correct |
539 ms |
31144 KB |
Output is correct |
37 |
Correct |
546 ms |
29868 KB |
Output is correct |
38 |
Correct |
532 ms |
29816 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
15196 KB |
Output is correct |
2 |
Correct |
9 ms |
15196 KB |
Output is correct |
3 |
Correct |
10 ms |
15192 KB |
Output is correct |
4 |
Correct |
9 ms |
15196 KB |
Output is correct |
5 |
Correct |
9 ms |
15196 KB |
Output is correct |
6 |
Correct |
10 ms |
15196 KB |
Output is correct |
7 |
Correct |
10 ms |
15196 KB |
Output is correct |
8 |
Correct |
14 ms |
15196 KB |
Output is correct |
9 |
Correct |
14 ms |
15196 KB |
Output is correct |
10 |
Correct |
11 ms |
15192 KB |
Output is correct |
11 |
Correct |
9 ms |
15196 KB |
Output is correct |
12 |
Correct |
10 ms |
15192 KB |
Output is correct |
13 |
Correct |
9 ms |
15196 KB |
Output is correct |
14 |
Correct |
9 ms |
15196 KB |
Output is correct |
15 |
Correct |
9 ms |
15196 KB |
Output is correct |
16 |
Correct |
6 ms |
15196 KB |
Output is correct |
17 |
Correct |
6 ms |
15196 KB |
Output is correct |
18 |
Correct |
6 ms |
15196 KB |
Output is correct |
19 |
Correct |
6 ms |
15324 KB |
Output is correct |
20 |
Correct |
6 ms |
15196 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
540 ms |
30032 KB |
Output is correct |
2 |
Correct |
550 ms |
29832 KB |
Output is correct |
3 |
Correct |
543 ms |
30864 KB |
Output is correct |
4 |
Correct |
540 ms |
30036 KB |
Output is correct |
5 |
Correct |
533 ms |
29896 KB |
Output is correct |
6 |
Correct |
534 ms |
33184 KB |
Output is correct |
7 |
Correct |
544 ms |
29896 KB |
Output is correct |
8 |
Correct |
533 ms |
30072 KB |
Output is correct |
9 |
Correct |
533 ms |
30036 KB |
Output is correct |
10 |
Correct |
532 ms |
30212 KB |
Output is correct |
11 |
Correct |
538 ms |
30084 KB |
Output is correct |
12 |
Correct |
535 ms |
30116 KB |
Output is correct |
13 |
Correct |
532 ms |
30208 KB |
Output is correct |
14 |
Correct |
533 ms |
32968 KB |
Output is correct |
15 |
Correct |
534 ms |
30064 KB |
Output is correct |
16 |
Correct |
98 ms |
21916 KB |
Output is correct |
17 |
Correct |
103 ms |
22040 KB |
Output is correct |
18 |
Correct |
100 ms |
21904 KB |
Output is correct |
19 |
Correct |
104 ms |
21908 KB |
Output is correct |
20 |
Correct |
101 ms |
21920 KB |
Output is correct |
21 |
Correct |
565 ms |
30956 KB |
Output is correct |
22 |
Correct |
566 ms |
31000 KB |
Output is correct |
23 |
Correct |
551 ms |
31056 KB |
Output is correct |
24 |
Correct |
564 ms |
31124 KB |
Output is correct |
25 |
Correct |
568 ms |
32300 KB |
Output is correct |
26 |
Correct |
598 ms |
30676 KB |
Output is correct |
27 |
Correct |
602 ms |
31808 KB |
Output is correct |
28 |
Correct |
631 ms |
31668 KB |
Output is correct |
29 |
Correct |
598 ms |
31644 KB |
Output is correct |
30 |
Correct |
530 ms |
30032 KB |
Output is correct |
31 |
Correct |
546 ms |
29932 KB |
Output is correct |
32 |
Correct |
540 ms |
30964 KB |
Output is correct |
33 |
Correct |
543 ms |
29864 KB |
Output is correct |
34 |
Correct |
538 ms |
30072 KB |
Output is correct |
35 |
Correct |
539 ms |
31400 KB |
Output is correct |
36 |
Correct |
539 ms |
31144 KB |
Output is correct |
37 |
Correct |
546 ms |
29868 KB |
Output is correct |
38 |
Correct |
532 ms |
29816 KB |
Output is correct |
39 |
Correct |
9 ms |
15196 KB |
Output is correct |
40 |
Correct |
9 ms |
15196 KB |
Output is correct |
41 |
Correct |
10 ms |
15192 KB |
Output is correct |
42 |
Correct |
9 ms |
15196 KB |
Output is correct |
43 |
Correct |
9 ms |
15196 KB |
Output is correct |
44 |
Correct |
10 ms |
15196 KB |
Output is correct |
45 |
Correct |
10 ms |
15196 KB |
Output is correct |
46 |
Correct |
14 ms |
15196 KB |
Output is correct |
47 |
Correct |
14 ms |
15196 KB |
Output is correct |
48 |
Correct |
11 ms |
15192 KB |
Output is correct |
49 |
Correct |
9 ms |
15196 KB |
Output is correct |
50 |
Correct |
10 ms |
15192 KB |
Output is correct |
51 |
Correct |
9 ms |
15196 KB |
Output is correct |
52 |
Correct |
9 ms |
15196 KB |
Output is correct |
53 |
Correct |
9 ms |
15196 KB |
Output is correct |
54 |
Correct |
6 ms |
15196 KB |
Output is correct |
55 |
Correct |
6 ms |
15196 KB |
Output is correct |
56 |
Correct |
6 ms |
15196 KB |
Output is correct |
57 |
Correct |
6 ms |
15324 KB |
Output is correct |
58 |
Correct |
6 ms |
15196 KB |
Output is correct |
59 |
Correct |
634 ms |
32420 KB |
Output is correct |
60 |
Correct |
620 ms |
32420 KB |
Output is correct |
61 |
Correct |
628 ms |
32328 KB |
Output is correct |
62 |
Correct |
628 ms |
32340 KB |
Output is correct |
63 |
Correct |
630 ms |
32260 KB |
Output is correct |
64 |
Correct |
721 ms |
33064 KB |
Output is correct |
65 |
Correct |
711 ms |
33104 KB |
Output is correct |
66 |
Correct |
721 ms |
33264 KB |
Output is correct |
67 |
Correct |
711 ms |
33168 KB |
Output is correct |
68 |
Correct |
719 ms |
33192 KB |
Output is correct |
69 |
Correct |
604 ms |
32420 KB |
Output is correct |
70 |
Correct |
611 ms |
32252 KB |
Output is correct |
71 |
Correct |
609 ms |
32248 KB |
Output is correct |
72 |
Correct |
608 ms |
32252 KB |
Output is correct |
73 |
Correct |
609 ms |
32244 KB |
Output is correct |
74 |
Correct |
109 ms |
23208 KB |
Output is correct |
75 |
Correct |
112 ms |
23376 KB |
Output is correct |
76 |
Correct |
112 ms |
23380 KB |
Output is correct |
77 |
Correct |
112 ms |
23380 KB |
Output is correct |
78 |
Correct |
111 ms |
23380 KB |
Output is correct |