#include <bits/stdc++.h>
#define ll long long
#define N 505
#define pii pair<int,int>
#define fi first
#define se second
#define pb emplace_back
const int oo = 1e9 + 7;
using namespace std;
int n,m;
pii a[N],b[N];
ll res,inv[N],dp[N][N*4],pre[N][N*4];
vector<int> lvt;
ll power(ll x,int y) {
if (y == 0) return 1;
ll tam = power(x*x %oo, y>>1);
if (y&1) tam = tam * x %oo;
return tam;
}
int main()
{
//freopen(".inp","r",stdin);
//freopen(".out","w",stdout);
ios_base::sync_with_stdio (0); cin.tie (0); cout.tie (0);
cin >> n;
for (int i=1;i<=n;++i) {
cin >> a[i].fi >> a[i].se;
lvt.pb(a[i].fi); lvt.pb(a[i].se);
}
sort(lvt.begin(),lvt.end());
lvt.resize(unique(lvt.begin(),lvt.end())-lvt.begin());
for (int e=0;e<(int)lvt.size();++e) {
b[++m] = {lvt[e],lvt[e]};
if (e < (int)lvt.size() - 1 && lvt[e]+1 < lvt[e+1]) b[++m] = {lvt[e]+1,lvt[e+1]-1};
}
dp[0][0] = 1;
for (int i=0;i<=n;++i) pre[i][0] = 1;
for (int j=0;j<=m;++j) pre[0][j] = 1;
for (int i=1;i<=n;++i) inv[i] = power(i,oo-2);
for (int i=1;i<=n;++i)
for (int j=1;j<=m;++j) {
dp[i][j] = dp[i][j-1];
if (a[i].fi > b[j].se || a[i].se < b[j].fi) {
pre[i][j] = (pre[i-1][j] + dp[i][j]) %oo;
continue;
}
int len = b[j].se - b[j].fi + 1; int num = -1;
ll C = len - 1;
dp[i][j] = (dp[i][j] + pre[i-1][j-1] * len) %oo;
if (len >= 2) {
for (int k=2;k<=i;++k) {
if (a[i-k+1].fi > b[j].se || a[i-k+1].se < b[j].fi) continue;
++num;
C = C * (num + len) %oo * inv[num+2] %oo;
dp[i][j] = (dp[i][j] + pre[i-k][j-1] * C) %oo;
}
}
pre[i][j] = (pre[i-1][j] + dp[i][j]) %oo;
}
for (int i=1;i<=n;++i) res = (res + dp[i][m]) %oo;
cout << res;
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
7 ms |
12116 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
7 ms |
12116 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
3 ms |
1748 KB |
Output is correct |
2 |
Correct |
3 ms |
1748 KB |
Output is correct |
3 |
Correct |
3 ms |
1748 KB |
Output is correct |
4 |
Correct |
3 ms |
1748 KB |
Output is correct |
5 |
Correct |
3 ms |
1772 KB |
Output is correct |
6 |
Correct |
5 ms |
1748 KB |
Output is correct |
7 |
Correct |
5 ms |
1748 KB |
Output is correct |
8 |
Correct |
5 ms |
1748 KB |
Output is correct |
9 |
Correct |
5 ms |
1748 KB |
Output is correct |
10 |
Correct |
5 ms |
1736 KB |
Output is correct |
11 |
Correct |
3 ms |
1748 KB |
Output is correct |
12 |
Correct |
2 ms |
1748 KB |
Output is correct |
13 |
Correct |
3 ms |
1748 KB |
Output is correct |
14 |
Correct |
2 ms |
1748 KB |
Output is correct |
15 |
Correct |
3 ms |
1748 KB |
Output is correct |
16 |
Correct |
2 ms |
1364 KB |
Output is correct |
17 |
Correct |
2 ms |
1364 KB |
Output is correct |
18 |
Correct |
2 ms |
1364 KB |
Output is correct |
19 |
Correct |
2 ms |
1364 KB |
Output is correct |
20 |
Correct |
2 ms |
1348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
7 ms |
12116 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |