#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i,s,e) for(int i = s; i <= (int)e; ++i)
#define DEC(i,s,e) for(int i = s; i >= (int)e; --i)
#define IAMSPEED ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef LOCAL
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{" << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
#define reach cerr << "LINE: " << __LINE__ << "\n";
#else
#define reach
#define db(x)
#define db2(x,y)
#define db3(a,b,c)
#define dbv(v)
#define dbvp(v)
#define dba(a,ss,ee)
#endif
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define pb push_back
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define f first
#define s second
#define g0(x) get<0>(x)
#define g1(x) get<1>(x)
#define g2(x) get<2>(x)
#define g3(x) get<3>(x)
typedef pair <int, int> pi;
typedef tuple<int,int,int> ti3;
typedef tuple<int,int,int,int> ti4;
int rand(int a, int b) { return a + rng() % (b-a+1); }
const int MOD = 1e9 + 7;
const int inf = (int)1e9 + 500;
const long long oo = (long long)1e18 + 500;
template <typename T> void chmax(T& a, const T b) { a=max(a,b); }
template <typename T> void chmin(T& a, const T b) { a=min(a,b); }
const int MAXN = 1005;
int n;
vector<int> points;
int L[MAXN],R[MAXN];
int dp[MAXN][MAXN]; // dp(i,c)=number of ways to reach the ith segment with c objects inside the ith segment
int S[MAXN];
int sz[MAXN];
int qexp(int a, int b, int mod) {
a%=mod;
int res = 1;
while(b) {
if(b&1)res=res*a%mod;
a=a*a%mod;
b>>=1;
}
return res;
}
int memo[MAXN][MAXN];
int choose(int n, int k) {
if(~memo[n][k])return memo[n][k];
int x = 1, y = 1;
FOR(i,0,k-1) {
y*=n-i;
x*=k-i;
y%=MOD;
x%=MOD;
}
return memo[n][k]=(y*qexp(x,MOD-2,MOD)) % MOD;
}
int32_t main()
{
IAMSPEED
memset(memo,-1,sizeof memo);
cin >> n;
FOR(i,1,n){
cin >> L[i] >> R[i];
points.pb(L[i]);
points.pb(R[i]+1);
}
points.pb(-inf);
sort(all(points));
points.resize(unique(all(points))-points.begin());
// my ith segment is points[i] to points[i+1]
int m=points.size();
FOR(i,0,m-2)sz[i]=points[i+1]-points[i];
FOR(i,0,m-1)S[i]=1;
FOR(i,1,n) {
int ls=lower_bound(all(points),L[i])-points.begin();
int rs=lower_bound(all(points),R[i]+1)-points.begin();
DEC(j,rs-1,ls){
DEC(k,min(sz[j],n),1){
if(k>1)dp[j][k]=(dp[j][k]+dp[j][k-1])%MOD;
else if(j)dp[j][k]=(dp[j][k]+S[j-1])%MOD;
db3(j,k,dp[j][k]);
}
}
memset(S,0,sizeof S);
FOR(j,0,m-1){
int val = 0;
if(j==0){
val=1;
}
FOR(k,1,min(n,sz[j])){
val=(val+dp[j][k]*choose(sz[j],k)%MOD)%MOD;
}
if(j)S[j]=(S[j-1]+val)%MOD;
else S[j]=1;
}
}
cout<<(S[m-1]-1+MOD)%MOD;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
11 ms |
16596 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
11 ms |
16596 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
13 ms |
17876 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
11 ms |
16596 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
