This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include "bits/stdc++.h"
using namespace std;
#define for_(i, s, e) for (int i = s; i < (int) e; i++)
#define for__(i, s, e) for (ll i = s; i < e; i++)
typedef long long ll;
typedef vector<int> vi;
typedef array<int, 2> ii;
// #define endl '\n'
const ll mod = 1e9+7;
ll power(ll x, ll y) {
if (y == 0) return 1;
ll p = power(x, y/2) % mod;
p = (p * p) % mod;
return (y%2 == 0)? p : (x * p) % mod;
}
ll modInverse(ll a) {
return power(a, mod-2);
}
const int MXN = 500;
ll choose[4*MXN+2][MXN+1], dp[2][MXN+1][MXN+1][2];
int main() {
#ifdef mlocal
freopen("test.in", "r", stdin);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
int n; cin >> n;
vector<ii> lt(n);
vi raw(2*n);
for_(i, 0, n) {
cin >> lt[i][0] >> lt[i][1];
raw[2*i] = lt[i][0], raw[2*i+1] = lt[i][1];
}
sort(raw.begin(), raw.end());
raw.resize(unique(raw.begin(), raw.end()) - raw.begin());
vector<ii> seg;
int pre = -1;
for_(i, 0, raw.size()) {
if (pre < raw[i] and pre != -1) seg.push_back({pre, raw[i]-1});
seg.push_back({raw[i], raw[i]});
pre = raw[i]+1;
}
int ns = seg.size();
// cout << ns << endl;
memset(choose, 0, sizeof(choose)); memset(dp, 0, sizeof(dp));
vector<ll> modInv(n+1);
for_(i, 1, n+1) modInv[i] = modInverse(i);
for_(i, 0, ns) {
choose[i][0] = 1;
for_(r, 1, min(n, seg[i][1]-seg[i][0]+1) + 1) choose[i][r] = (((choose[i][r-1] * (seg[i][1]-seg[i][0]-r+2)) % mod) * modInv[r]) % mod;
}
int c = 0;
for (int s = ns-1; s >= 0; s--) {
memset(dp[c], 0, sizeof(dp[c]));
for (int ct = min(n-1, seg[s][1]-seg[s][0]+1); ct >= 0; ct--) {
dp[c][ct][n][0] = choose[s][ct];
for (int idx = n-1; idx >= 0; idx--) {
if (seg[s][0] >= lt[idx][0] and seg[s][1] <= lt[idx][1]) dp[c][ct][idx][1] += dp[c][ct+1][idx+1][0];
if (dp[c][ct][idx][1] >= mod) dp[c][ct][idx][1] -= mod;
dp[c][ct][idx][1] += (choose[s][ct] * (s < ns-1 ? dp[1-c][0][idx][1] : 0)) % mod;
if (dp[c][ct][idx][1] >= mod) dp[c][ct][idx][1] -= mod;
dp[c][ct][idx][0] = dp[c][ct][idx][1] + dp[c][ct][idx+1][0];
if (dp[c][ct][idx][0] >= mod) dp[c][ct][idx][0] -= mod;
}
}
c = 1-c;
}
cout << (dp[1-c][0][0][0]-1+mod) % mod << endl;
}
Compilation message (stderr)
In file included from /usr/include/x86_64-linux-gnu/c++/9/bits/gthr.h:148,
from /usr/include/c++/9/ext/atomicity.h:35,
from /usr/include/c++/9/bits/ios_base.h:39,
from /usr/include/c++/9/ios:42,
from /usr/include/c++/9/istream:38,
from /usr/include/c++/9/sstream:38,
from /usr/include/c++/9/complex:45,
from /usr/include/c++/9/ccomplex:39,
from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:54,
from boat.cpp:4:
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:102:1: error: option("tune=") was already specified
102 | __gthrw(pthread_once)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:102:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:103:1: error: option("tune=") was already specified
103 | __gthrw(pthread_getspecific)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:103:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:104:1: error: option("tune=") was already specified
104 | __gthrw(pthread_setspecific)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:104:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:106:1: error: option("tune=") was already specified
106 | __gthrw(pthread_create)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:106:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:107:1: error: option("tune=") was already specified
107 | __gthrw(pthread_join)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:107:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:108:1: error: option("tune=") was already specified
108 | __gthrw(pthread_equal)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:108:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:109:1: error: option("tune=") was already specified
109 | __gthrw(pthread_self)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:109:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:110:1: error: option("tune=") was already specified
110 | __gthrw(pthread_detach)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:110:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:112:1: error: option("tune=") was already specified
112 | __gthrw(pthread_cancel)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:112:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:114:1: error: option("tune=") was already specified
114 | __gthrw(sched_yield)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:114:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:116:1: error: option("tune=") was already specified
116 | __gthrw(pthread_mutex_lock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:116:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:117:1: error: option("tune=") was already specified
117 | __gthrw(pthread_mutex_trylock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:117:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:119:1: error: option("tune=") was already specified
119 | __gthrw(pthread_mutex_timedlock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:119:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:121:1: error: option("tune=") was already specified
121 | __gthrw(pthread_mutex_unlock)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:121:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:122:1: error: option("tune=") was already specified
122 | __gthrw(pthread_mutex_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:122:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:123:1: error: option("tune=") was already specified
123 | __gthrw(pthread_mutex_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:123:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:125:1: error: option("tune=") was already specified
125 | __gthrw(pthread_cond_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:125:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:126:1: error: option("tune=") was already specified
126 | __gthrw(pthread_cond_broadcast)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:126:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:127:1: error: option("tune=") was already specified
127 | __gthrw(pthread_cond_signal)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:127:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:128:1: error: option("tune=") was already specified
128 | __gthrw(pthread_cond_wait)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:128:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:129:1: error: option("tune=") was already specified
129 | __gthrw(pthread_cond_timedwait)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:129:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:130:1: error: option("tune=") was already specified
130 | __gthrw(pthread_cond_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:130:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:132:1: error: option("tune=") was already specified
132 | __gthrw(pthread_key_create)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:132:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:133:1: error: option("tune=") was already specified
133 | __gthrw(pthread_key_delete)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:133:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:134:1: error: option("tune=") was already specified
134 | __gthrw(pthread_mutexattr_init)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:134:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:135:1: error: option("tune=") was already specified
135 | __gthrw(pthread_mutexattr_settype)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:135:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:136:1: error: option("tune=") was already specified
136 | __gthrw(pthread_mutexattr_destroy)
| ^~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:136:1: error: option("tune=") was already specified
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:237:1: error: option("tune=") was already specified
237 | __gthrw2(__gthrw_(__pthread_key_create),
| ^~~~~~~~
/usr/include/x86_64-linux-gnu/c++/9/bits/gthr-default.h:237:1: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:71:3: error: option("tune=") was already specified
71 | _GLIBCXX_GTHRW(rwlock_rdlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/9/shared_mutex:71:3: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:72:3: error: option("tune=") was already specified
72 | _GLIBCXX_GTHRW(rwlock_tryrdlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/9/shared_mutex:72:3: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:73:3: error: option("tune=") was already specified
73 | _GLIBCXX_GTHRW(rwlock_wrlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/9/shared_mutex:73:3: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:74:3: error: option("tune=") was already specified
74 | _GLIBCXX_GTHRW(rwlock_trywrlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/9/shared_mutex:74:3: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:75:3: error: option("tune=") was already specified
75 | _GLIBCXX_GTHRW(rwlock_unlock)
| ^~~~~~~~~~~~~~
/usr/include/c++/9/shared_mutex:75:3: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:89:4: error: option("tune=") was already specified
89 | __gthrw(pthread_rwlock_timedrdlock);
| ^~~~~~~
/usr/include/c++/9/shared_mutex:89:4: error: option("tune=") was already specified
/usr/include/c++/9/shared_mutex:99:4: error: option("tune=") was already specified
99 | __gthrw(pthread_rwlock_timedwrlock);
| ^~~~~~~
/usr/include/c++/9/shared_mutex:99:4: error: option("tune=") was already specified