#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
const int N = 505;
const int M = N * 4;
const int MOD = (int)1e9 + 7;
int L[N], R[N];
int C[M][N];
int I[N][N];
int fin[M][N];
int powr(int n, int k){
if(k == 0) return 1;
int p = powr(n, k / 2);
p = (p * 1ll * p) % MOD;
if(k % 2 == 1) p = (p * 1ll * n) % MOD;
return p;
}
void add(int &a, int b){
a += b;
if(a >= MOD) a -= MOD;
else if(a < 0) a += MOD;
}
int dp[N][M];
int main(){
fastIO;
//freopen("in.txt","r",stdin);
int n;
cin >> n;
vector<int> pp;
for(int i = 1; i <= n; i ++ ){
cin >> L[i] >> R[i];
pp.push_back(L[i]);
pp.push_back(R[i]);
}
sort(pp.begin(), pp.end());
pp.resize(unique(pp.begin(), pp.end()) - pp.begin());
vector<pii> segm;
for(int i = 0 ; i < pp.size(); i ++ ){
segm.push_back(mp(pp[i], pp[i]));
if(i + 1 < pp.size() && pp[i] + 1 <= pp[i + 1] - 1){
segm.push_back(mp(pp[i] + 1, pp[i + 1] - 1));
}
}
int m = segm.size();
for(int i = 1; i < N ;i ++ ){
I[i][0] = 1;
}
for(int k = 1; k < N ; k ++ ){
for(int i = 1; i < N ; i ++ ){
add(I[i][k], I[i-1][k-1]);
add(I[i][k], I[i][k-1]);
}
}
int sz;
int P, Q;
int inv;
int cum;
for(int i = 0 ; i < m ; i ++ ){
sz = segm[i].se - segm[i].fi + 1;
P = Q = 1;
for(int j = 1; j <= n; j ++ ){
if(j > sz) break;
P = (P * 1ll * (sz - j + 1)) % MOD;
Q = (Q * 1ll * j) % MOD;
inv = powr(Q, MOD - 2);
C[i][j] = (P * 1ll * inv) % MOD;
}
for(int j = 1; j <= n; j ++ ){
for(int v = 1; v <= j; v ++ ){
add(fin[i][j], C[i][v] * 1ll * I[j][v]);
}
}
for(int j = n; j >= 1; j -- ){
add(fin[i][j], -fin[i][j-1]);
}
}
int tl, tr;
int mm;
int side;
int res = 0;
for(int i = 1; i <= n; i ++ ){
for(int j = 0 ; j < m ; j ++ ){
tl = segm[j].fi;
tr = segm[j].se;
if(L[i] <= tl && tr <= R[i]){
mm = 0;
for(int v = i; v >= 1; v -- ){
if(L[v] <= tl && tr <= R[v]) mm ++ ;
side = 0;
if(j > 0) add(side, dp[v - 1][j - 1]);
if(v == 1) add(side, 1);
add(dp[i][j], (side * 1ll * fin[j][mm]) % MOD);
}
}
add(res, dp[i][j]);
if(j)
add(dp[i][j], dp[i][j-1]);
}
}
cout << res << "\n";
return 0;
}
Compilation message
boat.cpp: In function 'int main()':
boat.cpp:53:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
53 | for(int i = 0 ; i < pp.size(); i ++ ){
| ~~^~~~~~~~~~~
boat.cpp:55:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
55 | if(i + 1 < pp.size() && pp[i] + 1 <= pp[i + 1] - 1){
| ~~~~~~^~~~~~~~~~~
boat.cpp:72:9: warning: unused variable 'cum' [-Wunused-variable]
72 | int cum;
| ^~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
232 ms |
9320 KB |
Output is correct |
2 |
Correct |
226 ms |
9160 KB |
Output is correct |
3 |
Correct |
231 ms |
9284 KB |
Output is correct |
4 |
Correct |
230 ms |
9236 KB |
Output is correct |
5 |
Correct |
227 ms |
9156 KB |
Output is correct |
6 |
Correct |
232 ms |
9456 KB |
Output is correct |
7 |
Correct |
233 ms |
9156 KB |
Output is correct |
8 |
Correct |
233 ms |
9128 KB |
Output is correct |
9 |
Correct |
242 ms |
9368 KB |
Output is correct |
10 |
Correct |
225 ms |
9140 KB |
Output is correct |
11 |
Correct |
227 ms |
9156 KB |
Output is correct |
12 |
Correct |
229 ms |
9244 KB |
Output is correct |
13 |
Correct |
226 ms |
9156 KB |
Output is correct |
14 |
Correct |
226 ms |
9192 KB |
Output is correct |
15 |
Correct |
244 ms |
9268 KB |
Output is correct |
16 |
Incorrect |
43 ms |
4292 KB |
Output isn't correct |
17 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
232 ms |
9320 KB |
Output is correct |
2 |
Correct |
226 ms |
9160 KB |
Output is correct |
3 |
Correct |
231 ms |
9284 KB |
Output is correct |
4 |
Correct |
230 ms |
9236 KB |
Output is correct |
5 |
Correct |
227 ms |
9156 KB |
Output is correct |
6 |
Correct |
232 ms |
9456 KB |
Output is correct |
7 |
Correct |
233 ms |
9156 KB |
Output is correct |
8 |
Correct |
233 ms |
9128 KB |
Output is correct |
9 |
Correct |
242 ms |
9368 KB |
Output is correct |
10 |
Correct |
225 ms |
9140 KB |
Output is correct |
11 |
Correct |
227 ms |
9156 KB |
Output is correct |
12 |
Correct |
229 ms |
9244 KB |
Output is correct |
13 |
Correct |
226 ms |
9156 KB |
Output is correct |
14 |
Correct |
226 ms |
9192 KB |
Output is correct |
15 |
Correct |
244 ms |
9268 KB |
Output is correct |
16 |
Incorrect |
43 ms |
4292 KB |
Output isn't correct |
17 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
16 ms |
3388 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
232 ms |
9320 KB |
Output is correct |
2 |
Correct |
226 ms |
9160 KB |
Output is correct |
3 |
Correct |
231 ms |
9284 KB |
Output is correct |
4 |
Correct |
230 ms |
9236 KB |
Output is correct |
5 |
Correct |
227 ms |
9156 KB |
Output is correct |
6 |
Correct |
232 ms |
9456 KB |
Output is correct |
7 |
Correct |
233 ms |
9156 KB |
Output is correct |
8 |
Correct |
233 ms |
9128 KB |
Output is correct |
9 |
Correct |
242 ms |
9368 KB |
Output is correct |
10 |
Correct |
225 ms |
9140 KB |
Output is correct |
11 |
Correct |
227 ms |
9156 KB |
Output is correct |
12 |
Correct |
229 ms |
9244 KB |
Output is correct |
13 |
Correct |
226 ms |
9156 KB |
Output is correct |
14 |
Correct |
226 ms |
9192 KB |
Output is correct |
15 |
Correct |
244 ms |
9268 KB |
Output is correct |
16 |
Incorrect |
43 ms |
4292 KB |
Output isn't correct |
17 |
Halted |
0 ms |
0 KB |
- |