//Power Of Ninja Go
#include <bits/stdc++.h>
//#ifdef atom #else #endif
using namespace std;
typedef long long ll; typedef pair<int, int> ii; typedef vector<int> vi; typedef vector< ii > vii;
#define X first
#define Y second
#define pb push_back
const int maxn = 505;
const int md = 1e9+7;
void add(int &a, int b)
{
a += b;
if(a>= md) a-= md;
}
int mul(int a, int b)
{
return (1LL*a*b)%md;
}
int expo(int a, int b)
{
if(b == 0) return 1;
int x = expo(a, b/2);
int y = mul(x, x);
if(b%2) y = mul(y, a);
return y;
}
int inv(int x)
{
return expo(x, md-2);
}
int a[maxn];
int b[maxn];
int qu[maxn][2*maxn];
int f[maxn][2*maxn];
int sum[maxn][2*maxn];
int n;
vi vec;
int g(int L, int R, int intv)
{
//cout << L << ' ' << R << ' ' << intv << endl;
int k = qu[R][intv]-qu[L-1][intv]-1;
int sz = vec[intv+1]-vec[intv];
int res = 1;
//cout << sz << ' ' << k << endl;
for(int i = sz; i<= sz+k; i++) res = mul(res, i);
for(int i = 1; i<= k+1; i++) res = mul(res, inv(i));
return res;
}
int main()
{
cin >> n;
for(int i = 1; i<= n; i++)
{
cin >> a[i] >> b[i];
b[i]++;
vec.pb(a[i]); vec.pb(b[i]);
}
sort(vec.begin(), vec.end()); vec.resize(unique(vec.begin(), vec.end())-vec.begin());
for(int i = 1; i<= n; i++)
{
a[i] = lower_bound(vec.begin(), vec.end(), a[i])-vec.begin();
b[i] = lower_bound(vec.begin(), vec.end(), b[i])-vec.begin();
}
for(int i = 1; i<= n; i++)
{
for(int j = 0; j< (int) vec.size()-1; j++)
{
qu[i][j] = qu[i-1][j] + (a[i]<= j && j< b[i]);
}
}
for(int j = 0; j< (int) vec.size()-1; j++) sum[0][j] = 1;
for(int i = 1; i<= n; i++)
{
for(int j = 0; j< (int) vec.size()-1; j++)
{
if(!(a[i]<= j && j <b[i])) continue;
for(int a = 0; a< i; a++)
{
int sm;
if(j == 0) sm = 1;
else sm = sum[a][j-1];
add(f[i][j], mul(sm, g(a+1, i, j)));
}
sum[i][j] = sum[i][j-1];
add(sum[i][j], f[i][j]);
}
}
int res = 0;
for(int i = 1; i<= n; i++)
{
for(int j = 0; j< (int) vec.size()-1; j++)
{
add(res, f[i][j]);
}
}
cout << res << endl;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
65 ms |
5752 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
65 ms |
5752 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
1596 ms |
5752 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
65 ms |
5752 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |