#include <bits/stdc++.h>
using namespace std;
void just_do_it();
int main() {
#ifdef KAMIRULEZ
freopen("kamirulez.inp", "r", stdin);
freopen("kamirulez.out", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(0);
just_do_it();
return 0;
}
const int maxn = 5e2 + 20;
const long long mod = 1e9 + 7;
bool flag[maxn];
long long inv[maxn];
long long fact_inv[maxn];
long long cur[maxn];
long long nxt[maxn];
pair<int, int> events[maxn * 2];
int n;
void trans() {
for (int i = 1; i <= n; i++) {
if (flag[i]) {
nxt[i] = cur[i] + 1;
if (nxt[i] >= mod) {
nxt[i] -= mod;
}
}
else {
nxt[i] = cur[i];
}
}
for (int i = 1; i <= n; i++) {
for (int j = i + 1; j <= n; j++) {
if (flag[j]) {
nxt[j] += cur[i];
if (nxt[j] >= mod) {
nxt[j] -= mod;
}
}
}
}
swap(cur, nxt);
}
long long choose(int x, int y) {
if (x < y) {
return 0;
}
long long res = fact_inv[y];
for (int i = 0; i < y; i++) {
res = res * (x - i) % mod;
}
return res;
}
void shift(int len) {
for (int i = 1; i <= n; i++) {
if (flag[i]) {
nxt[i] = (cur[i] + len) % mod;
}
else {
nxt[i] = cur[i];
}
}
for (int i = 1; i <= n; i++) {
int cnt = 0;
for (int j = i + 1; j <= n; j++) {
if (flag[j]) {
cnt++;
if (flag[i]) {
nxt[j] = (nxt[j] + cur[i] * choose(len + cnt - 1, cnt) + choose(len + cnt - 1, cnt + 1)) % mod;
}
else {
nxt[j] = (nxt[j] + cur[i] * choose(len + cnt - 1, cnt)) % mod;
}
}
}
}
swap(cur, nxt);
}
void just_do_it() {
inv[1] = 1;
fact_inv[0] = 1;
fact_inv[1] = 1;
for (int i = 2; i < maxn; i++) {
inv[i] = (mod - mod / i) * inv[mod % i] % mod;
fact_inv[i] = fact_inv[i - 1] * inv[i] % mod;
}
cin >> n;
for (int i = 1; i <= n; i++) {
int a, b;
cin >> a >> b;
events[i * 2 - 1] = make_pair(a, i);
events[i * 2] = make_pair(b + 1, -i);
}
sort(events + 1, events + n * 2 + 1);
int cur_t = 0;
for (int i = 1; i <= n * 2; i++) {
int nxt_t = events[i].first;
int id = events[i].second;
bool begin_t = (i == 1 || events[i].first != events[i - 1].first);
bool end_t = (i == n * 2 || events[i].first != events[i + 1].first);
if (begin_t) {
if (cur_t < nxt_t - 1) {
shift(nxt_t - 1 - cur_t);
cur_t = nxt_t - 1;
}
}
if (id > 0) {
flag[id] = true;
}
else {
flag[-id] = false;
}
if (end_t && cur_t == nxt_t - 1) {
trans();
cur_t = nxt_t;
}
}
long long res = 0;
for (int i = 1; i <= n; i++) {
res += cur[i];
res %= mod;
}
cout << res;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
148 ms |
332 KB |
Output is correct |
2 |
Correct |
140 ms |
340 KB |
Output is correct |
3 |
Correct |
139 ms |
340 KB |
Output is correct |
4 |
Correct |
142 ms |
340 KB |
Output is correct |
5 |
Correct |
137 ms |
340 KB |
Output is correct |
6 |
Correct |
137 ms |
340 KB |
Output is correct |
7 |
Correct |
144 ms |
340 KB |
Output is correct |
8 |
Correct |
142 ms |
212 KB |
Output is correct |
9 |
Correct |
163 ms |
340 KB |
Output is correct |
10 |
Correct |
137 ms |
340 KB |
Output is correct |
11 |
Correct |
143 ms |
340 KB |
Output is correct |
12 |
Correct |
143 ms |
212 KB |
Output is correct |
13 |
Correct |
137 ms |
340 KB |
Output is correct |
14 |
Correct |
139 ms |
340 KB |
Output is correct |
15 |
Correct |
156 ms |
320 KB |
Output is correct |
16 |
Correct |
30 ms |
212 KB |
Output is correct |
17 |
Correct |
29 ms |
340 KB |
Output is correct |
18 |
Correct |
27 ms |
212 KB |
Output is correct |
19 |
Correct |
28 ms |
340 KB |
Output is correct |
20 |
Correct |
27 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
148 ms |
332 KB |
Output is correct |
2 |
Correct |
140 ms |
340 KB |
Output is correct |
3 |
Correct |
139 ms |
340 KB |
Output is correct |
4 |
Correct |
142 ms |
340 KB |
Output is correct |
5 |
Correct |
137 ms |
340 KB |
Output is correct |
6 |
Correct |
137 ms |
340 KB |
Output is correct |
7 |
Correct |
144 ms |
340 KB |
Output is correct |
8 |
Correct |
142 ms |
212 KB |
Output is correct |
9 |
Correct |
163 ms |
340 KB |
Output is correct |
10 |
Correct |
137 ms |
340 KB |
Output is correct |
11 |
Correct |
143 ms |
340 KB |
Output is correct |
12 |
Correct |
143 ms |
212 KB |
Output is correct |
13 |
Correct |
137 ms |
340 KB |
Output is correct |
14 |
Correct |
139 ms |
340 KB |
Output is correct |
15 |
Correct |
156 ms |
320 KB |
Output is correct |
16 |
Correct |
30 ms |
212 KB |
Output is correct |
17 |
Correct |
29 ms |
340 KB |
Output is correct |
18 |
Correct |
27 ms |
212 KB |
Output is correct |
19 |
Correct |
28 ms |
340 KB |
Output is correct |
20 |
Correct |
27 ms |
340 KB |
Output is correct |
21 |
Execution timed out |
2059 ms |
340 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
31 ms |
212 KB |
Output is correct |
2 |
Correct |
22 ms |
212 KB |
Output is correct |
3 |
Correct |
29 ms |
332 KB |
Output is correct |
4 |
Correct |
34 ms |
212 KB |
Output is correct |
5 |
Correct |
36 ms |
212 KB |
Output is correct |
6 |
Correct |
88 ms |
212 KB |
Output is correct |
7 |
Correct |
87 ms |
212 KB |
Output is correct |
8 |
Correct |
85 ms |
212 KB |
Output is correct |
9 |
Correct |
87 ms |
316 KB |
Output is correct |
10 |
Correct |
87 ms |
212 KB |
Output is correct |
11 |
Correct |
33 ms |
212 KB |
Output is correct |
12 |
Correct |
20 ms |
332 KB |
Output is correct |
13 |
Correct |
25 ms |
320 KB |
Output is correct |
14 |
Correct |
27 ms |
212 KB |
Output is correct |
15 |
Correct |
32 ms |
212 KB |
Output is correct |
16 |
Correct |
15 ms |
336 KB |
Output is correct |
17 |
Correct |
13 ms |
332 KB |
Output is correct |
18 |
Correct |
13 ms |
336 KB |
Output is correct |
19 |
Correct |
12 ms |
332 KB |
Output is correct |
20 |
Correct |
16 ms |
336 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
148 ms |
332 KB |
Output is correct |
2 |
Correct |
140 ms |
340 KB |
Output is correct |
3 |
Correct |
139 ms |
340 KB |
Output is correct |
4 |
Correct |
142 ms |
340 KB |
Output is correct |
5 |
Correct |
137 ms |
340 KB |
Output is correct |
6 |
Correct |
137 ms |
340 KB |
Output is correct |
7 |
Correct |
144 ms |
340 KB |
Output is correct |
8 |
Correct |
142 ms |
212 KB |
Output is correct |
9 |
Correct |
163 ms |
340 KB |
Output is correct |
10 |
Correct |
137 ms |
340 KB |
Output is correct |
11 |
Correct |
143 ms |
340 KB |
Output is correct |
12 |
Correct |
143 ms |
212 KB |
Output is correct |
13 |
Correct |
137 ms |
340 KB |
Output is correct |
14 |
Correct |
139 ms |
340 KB |
Output is correct |
15 |
Correct |
156 ms |
320 KB |
Output is correct |
16 |
Correct |
30 ms |
212 KB |
Output is correct |
17 |
Correct |
29 ms |
340 KB |
Output is correct |
18 |
Correct |
27 ms |
212 KB |
Output is correct |
19 |
Correct |
28 ms |
340 KB |
Output is correct |
20 |
Correct |
27 ms |
340 KB |
Output is correct |
21 |
Execution timed out |
2059 ms |
340 KB |
Time limit exceeded |
22 |
Halted |
0 ms |
0 KB |
- |