#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
const ll md = 1e9+7;
const int N = 500;
ll dp[N][2*N+1], dp_sum[N][2*N+1], C[2*N+1][N+1];
namespace combi{
const int n = 2e6;
ll fac[n], facinv[n];
ll pw(ll x, ll p){
if(p == 0) return 1;
if(p%2 == 0) return pw((x*x)%md, p/2);
return (pw(x, p-1)*x)%md;
}
void init(){
fac[0] = 1, facinv[0] = 1;
for(int i = 1; i < n; i++) fac[i] = (fac[i-1]*i)%md, facinv[i] = (facinv[i-1]*pw(i, md-2))%md;
}
ll nCr(int n, int r){
if(r > n) return 0;
ll rt = (fac[n]*facinv[r]);
rt%=md;
rt*=facinv[n-r];
rt%=md;
return rt;
}
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
combi::init();
int n; cin >> n;
vector<int> L(n), R(n);
vector<int> ranges, _ranges;
for(int i = 0; i < n; i++) cin >> L[i] >> R[i], _ranges.pb(L[i]), _ranges.pb(R[i]), _ranges.pb(R[i]+1);
sort(_ranges.begin(), _ranges.end());
for(int x: _ranges)
if(ranges.empty() || ranges.back() != x) ranges.pb(x);
int m = int(ranges.size())-1;
for(int i = 0; i < m; i++){
int x = ranges[i+1]-ranges[i];
for(int j = 0; j <= n; j++){
C[i][j] = 0;
for(int k = 0; k <= j; k++)
C[i][j]+=(combi::nCr(x, k+1)*combi::nCr(j, k))%md;
C[i][j]%=md;
}
}
auto nested = [&](int j, int i){
return ranges[j] >= L[i] && ranges[j+1]-1 <= R[i];
};
for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) dp[i][j] = 0, dp_sum[i][j] = 0;
for(int i = 0; i < n; i++){
for(int j = 0; j < m; j++){
if(!nested(j, i)) continue;
int c = 0;
for(int k = i; k >= 0; k--){
if(j == 0 && k) continue;
if(!nested(j, k)) c++;
dp[i][j]+=(C[j][i-k-c]*(k ? dp_sum[k-1][j-1]:1))%md;
dp[i][j]%=md;
}
}
for(int j = 0; j < m; j++){
if(j) dp_sum[i][j] = dp_sum[i][j-1];
dp_sum[i][j]+=dp[i][j];
dp_sum[i][j]%=md;
}
}
ll ans = 0;
for(int i = 0; i < n; i++) for(int j = 0; j < m; j++) ans+=dp[i][j], ans%=md;
cout << ans << "\n";
}
Compilation message
boat.cpp: In function 'int main()':
boat.cpp:54:13: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
54 | for(int k = 0; k <= j; k++)
| ^~~
boat.cpp:56:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
56 | C[i][j]%=md;
| ^
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
582 ms |
65112 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
582 ms |
65112 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
411 ms |
63860 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Runtime error |
582 ms |
65112 KB |
Execution killed with signal 11 |
2 |
Halted |
0 ms |
0 KB |
- |