#include<bits/stdc++.h>
using namespace std;
using ll=long long;
#define eb emplace_back
const ll md=1e9+7;
vector<int> comp;
int a[505],b[505];
ll dp[505][1005],inv[505],C[505][505],f[1005][505],g[1005][505];
int main(){
ios::sync_with_stdio(false); cin.tie(0);
int n; cin>>n;
for(int i=1;i<=n;++i){
cin>>a[i]>>b[i];
comp.eb(--a[i]), comp.eb(b[i]);
}
comp.eb(0);
sort(comp.begin(),comp.end());
comp.erase(unique(comp.begin(),comp.end()),comp.end());
C[0][0]=1;
for(int i=1;i<=n;++i){
inv[i]=1;
ll a=i,b=md-2;
for(;b>0;b>>=1,a=(a*a)%md) if(b&1) inv[i]=(inv[i]*a)%md;
C[i][0]=1;
for(int j=1;j<=n;++j) C[i][j]=(C[i-1][j-1]+C[i-1][j])%md;
}
for(int i=1;i<comp.size();++i){
int cur=comp[i]-comp[i-1];
f[i][1]=cur--;
for(int j=2;j<=n&&cur>0;++j) f[i][j]=((((f[i][j-1]*(cur--))%md)*inv[j])%md+md)%md;
for(int j=1;j<=n;++j){
int m=min(j,comp[i]-comp[i-1]);
for(int k=1;k<=m;++k) g[i][j]=(g[i][j]+f[i][k]*C[j-1][k-1])%md;
}
}
ll ans=0;
for(int i=1;i<=n;++i){
a[i]=lower_bound(comp.begin(),comp.end(),a[i])-comp.begin();
b[i]=lower_bound(comp.begin(),comp.end(),b[i])-comp.begin();
for(int j=a[i]+1;j<=b[i];++j){
int cnt=1;
for(int k=i-1;k>0;--k){
if(a[k]<j-1) dp[i][j]=(dp[i][j]+dp[k][min(b[k],j-1)]*g[j][cnt])%md;
if(a[k]<j&&j<=b[k]) ++cnt;
}
dp[i][j]=(dp[i][j]+dp[i][j-1]+g[j][cnt])%md;
}
ans=(ans+dp[i][b[i]])%md;
}
cout<<ans;
return 0;
}
/*
f[j][1]*C[cnt-1][1-1] + f[j][2]*C[cnt-1][2-1] + f[j][3]*C[cnt-1][3-1] + ... + f[j][min(m,cnt)]*C[cnt-1][min(m,cnt)-1]
f[1][1]*C[1][0]+f[1][2]*C[1][1]
*/
Compilation message
boat.cpp: In function 'int main()':
boat.cpp:32:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
32 | for(int i=1;i<comp.size();++i){
| ~^~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
240 ms |
12432 KB |
Output is correct |
2 |
Correct |
241 ms |
12368 KB |
Output is correct |
3 |
Correct |
239 ms |
12436 KB |
Output is correct |
4 |
Correct |
240 ms |
12452 KB |
Output is correct |
5 |
Correct |
238 ms |
12436 KB |
Output is correct |
6 |
Correct |
239 ms |
12628 KB |
Output is correct |
7 |
Correct |
239 ms |
12428 KB |
Output is correct |
8 |
Correct |
241 ms |
12560 KB |
Output is correct |
9 |
Correct |
239 ms |
12552 KB |
Output is correct |
10 |
Correct |
238 ms |
12624 KB |
Output is correct |
11 |
Correct |
244 ms |
12428 KB |
Output is correct |
12 |
Correct |
239 ms |
12560 KB |
Output is correct |
13 |
Correct |
240 ms |
12628 KB |
Output is correct |
14 |
Correct |
239 ms |
12628 KB |
Output is correct |
15 |
Correct |
241 ms |
12428 KB |
Output is correct |
16 |
Correct |
46 ms |
11028 KB |
Output is correct |
17 |
Correct |
49 ms |
11088 KB |
Output is correct |
18 |
Correct |
47 ms |
10920 KB |
Output is correct |
19 |
Correct |
48 ms |
11180 KB |
Output is correct |
20 |
Correct |
47 ms |
10912 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
240 ms |
12432 KB |
Output is correct |
2 |
Correct |
241 ms |
12368 KB |
Output is correct |
3 |
Correct |
239 ms |
12436 KB |
Output is correct |
4 |
Correct |
240 ms |
12452 KB |
Output is correct |
5 |
Correct |
238 ms |
12436 KB |
Output is correct |
6 |
Correct |
239 ms |
12628 KB |
Output is correct |
7 |
Correct |
239 ms |
12428 KB |
Output is correct |
8 |
Correct |
241 ms |
12560 KB |
Output is correct |
9 |
Correct |
239 ms |
12552 KB |
Output is correct |
10 |
Correct |
238 ms |
12624 KB |
Output is correct |
11 |
Correct |
244 ms |
12428 KB |
Output is correct |
12 |
Correct |
239 ms |
12560 KB |
Output is correct |
13 |
Correct |
240 ms |
12628 KB |
Output is correct |
14 |
Correct |
239 ms |
12628 KB |
Output is correct |
15 |
Correct |
241 ms |
12428 KB |
Output is correct |
16 |
Correct |
46 ms |
11028 KB |
Output is correct |
17 |
Correct |
49 ms |
11088 KB |
Output is correct |
18 |
Correct |
47 ms |
10920 KB |
Output is correct |
19 |
Correct |
48 ms |
11180 KB |
Output is correct |
20 |
Correct |
47 ms |
10912 KB |
Output is correct |
21 |
Correct |
147 ms |
13420 KB |
Output is correct |
22 |
Correct |
133 ms |
13320 KB |
Output is correct |
23 |
Correct |
138 ms |
13408 KB |
Output is correct |
24 |
Correct |
140 ms |
13392 KB |
Output is correct |
25 |
Correct |
132 ms |
13392 KB |
Output is correct |
26 |
Correct |
231 ms |
14100 KB |
Output is correct |
27 |
Correct |
234 ms |
14000 KB |
Output is correct |
28 |
Correct |
232 ms |
13916 KB |
Output is correct |
29 |
Correct |
227 ms |
13964 KB |
Output is correct |
30 |
Correct |
228 ms |
12468 KB |
Output is correct |
31 |
Correct |
232 ms |
12668 KB |
Output is correct |
32 |
Correct |
235 ms |
12576 KB |
Output is correct |
33 |
Correct |
231 ms |
12516 KB |
Output is correct |
34 |
Correct |
232 ms |
12592 KB |
Output is correct |
35 |
Correct |
225 ms |
12592 KB |
Output is correct |
36 |
Correct |
228 ms |
12444 KB |
Output is correct |
37 |
Correct |
230 ms |
12440 KB |
Output is correct |
38 |
Correct |
228 ms |
12472 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
7 ms |
9560 KB |
Output is correct |
2 |
Correct |
7 ms |
9564 KB |
Output is correct |
3 |
Correct |
7 ms |
9564 KB |
Output is correct |
4 |
Correct |
7 ms |
9560 KB |
Output is correct |
5 |
Correct |
7 ms |
9564 KB |
Output is correct |
6 |
Correct |
8 ms |
9564 KB |
Output is correct |
7 |
Correct |
8 ms |
9452 KB |
Output is correct |
8 |
Correct |
8 ms |
9560 KB |
Output is correct |
9 |
Correct |
8 ms |
9564 KB |
Output is correct |
10 |
Correct |
8 ms |
9640 KB |
Output is correct |
11 |
Correct |
7 ms |
9816 KB |
Output is correct |
12 |
Correct |
6 ms |
9564 KB |
Output is correct |
13 |
Correct |
7 ms |
9560 KB |
Output is correct |
14 |
Correct |
7 ms |
9564 KB |
Output is correct |
15 |
Correct |
7 ms |
9540 KB |
Output is correct |
16 |
Correct |
4 ms |
9304 KB |
Output is correct |
17 |
Correct |
6 ms |
9052 KB |
Output is correct |
18 |
Correct |
4 ms |
9052 KB |
Output is correct |
19 |
Correct |
4 ms |
9060 KB |
Output is correct |
20 |
Correct |
4 ms |
9052 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
240 ms |
12432 KB |
Output is correct |
2 |
Correct |
241 ms |
12368 KB |
Output is correct |
3 |
Correct |
239 ms |
12436 KB |
Output is correct |
4 |
Correct |
240 ms |
12452 KB |
Output is correct |
5 |
Correct |
238 ms |
12436 KB |
Output is correct |
6 |
Correct |
239 ms |
12628 KB |
Output is correct |
7 |
Correct |
239 ms |
12428 KB |
Output is correct |
8 |
Correct |
241 ms |
12560 KB |
Output is correct |
9 |
Correct |
239 ms |
12552 KB |
Output is correct |
10 |
Correct |
238 ms |
12624 KB |
Output is correct |
11 |
Correct |
244 ms |
12428 KB |
Output is correct |
12 |
Correct |
239 ms |
12560 KB |
Output is correct |
13 |
Correct |
240 ms |
12628 KB |
Output is correct |
14 |
Correct |
239 ms |
12628 KB |
Output is correct |
15 |
Correct |
241 ms |
12428 KB |
Output is correct |
16 |
Correct |
46 ms |
11028 KB |
Output is correct |
17 |
Correct |
49 ms |
11088 KB |
Output is correct |
18 |
Correct |
47 ms |
10920 KB |
Output is correct |
19 |
Correct |
48 ms |
11180 KB |
Output is correct |
20 |
Correct |
47 ms |
10912 KB |
Output is correct |
21 |
Correct |
147 ms |
13420 KB |
Output is correct |
22 |
Correct |
133 ms |
13320 KB |
Output is correct |
23 |
Correct |
138 ms |
13408 KB |
Output is correct |
24 |
Correct |
140 ms |
13392 KB |
Output is correct |
25 |
Correct |
132 ms |
13392 KB |
Output is correct |
26 |
Correct |
231 ms |
14100 KB |
Output is correct |
27 |
Correct |
234 ms |
14000 KB |
Output is correct |
28 |
Correct |
232 ms |
13916 KB |
Output is correct |
29 |
Correct |
227 ms |
13964 KB |
Output is correct |
30 |
Correct |
228 ms |
12468 KB |
Output is correct |
31 |
Correct |
232 ms |
12668 KB |
Output is correct |
32 |
Correct |
235 ms |
12576 KB |
Output is correct |
33 |
Correct |
231 ms |
12516 KB |
Output is correct |
34 |
Correct |
232 ms |
12592 KB |
Output is correct |
35 |
Correct |
225 ms |
12592 KB |
Output is correct |
36 |
Correct |
228 ms |
12444 KB |
Output is correct |
37 |
Correct |
230 ms |
12440 KB |
Output is correct |
38 |
Correct |
228 ms |
12472 KB |
Output is correct |
39 |
Correct |
7 ms |
9560 KB |
Output is correct |
40 |
Correct |
7 ms |
9564 KB |
Output is correct |
41 |
Correct |
7 ms |
9564 KB |
Output is correct |
42 |
Correct |
7 ms |
9560 KB |
Output is correct |
43 |
Correct |
7 ms |
9564 KB |
Output is correct |
44 |
Correct |
8 ms |
9564 KB |
Output is correct |
45 |
Correct |
8 ms |
9452 KB |
Output is correct |
46 |
Correct |
8 ms |
9560 KB |
Output is correct |
47 |
Correct |
8 ms |
9564 KB |
Output is correct |
48 |
Correct |
8 ms |
9640 KB |
Output is correct |
49 |
Correct |
7 ms |
9816 KB |
Output is correct |
50 |
Correct |
6 ms |
9564 KB |
Output is correct |
51 |
Correct |
7 ms |
9560 KB |
Output is correct |
52 |
Correct |
7 ms |
9564 KB |
Output is correct |
53 |
Correct |
7 ms |
9540 KB |
Output is correct |
54 |
Correct |
4 ms |
9304 KB |
Output is correct |
55 |
Correct |
6 ms |
9052 KB |
Output is correct |
56 |
Correct |
4 ms |
9052 KB |
Output is correct |
57 |
Correct |
4 ms |
9060 KB |
Output is correct |
58 |
Correct |
4 ms |
9052 KB |
Output is correct |
59 |
Correct |
615 ms |
13436 KB |
Output is correct |
60 |
Correct |
606 ms |
13604 KB |
Output is correct |
61 |
Correct |
588 ms |
13456 KB |
Output is correct |
62 |
Correct |
619 ms |
13336 KB |
Output is correct |
63 |
Correct |
605 ms |
13488 KB |
Output is correct |
64 |
Correct |
722 ms |
14228 KB |
Output is correct |
65 |
Correct |
722 ms |
14200 KB |
Output is correct |
66 |
Correct |
714 ms |
14220 KB |
Output is correct |
67 |
Correct |
724 ms |
14088 KB |
Output is correct |
68 |
Correct |
719 ms |
14120 KB |
Output is correct |
69 |
Correct |
604 ms |
13412 KB |
Output is correct |
70 |
Correct |
601 ms |
13456 KB |
Output is correct |
71 |
Correct |
594 ms |
13308 KB |
Output is correct |
72 |
Correct |
605 ms |
13540 KB |
Output is correct |
73 |
Correct |
603 ms |
13452 KB |
Output is correct |
74 |
Correct |
80 ms |
11096 KB |
Output is correct |
75 |
Correct |
77 ms |
11092 KB |
Output is correct |
76 |
Correct |
83 ms |
11548 KB |
Output is correct |
77 |
Correct |
79 ms |
11348 KB |
Output is correct |
78 |
Correct |
84 ms |
11344 KB |
Output is correct |