/*
Solution for APIO 2016 - Boat
Tags :
*/
#include <bits/stdc++.h>
using namespace std;
#pragma GCC target ("avx2")
#pragma GCC optimization ("Ofast")
#pragma GCC optimization ("unroll-loops")
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long double ld;
typedef pair<ll, ll> pll;
#define FOR(i, a, b) for(int i = a; i < b; i++)
#define ROF(i, a, b) for(int i = a; i >= b; i--)
#define ms memset
#define pb push_back
#define fi first
#define se second
ll MOD = 1000000007;
ll power(ll base, ll n){
if (n == 0) return 1;
if (n == 1) return base;
ll halfn = power(base, n/2);
if (n % 2 == 0) return (halfn * halfn) % MOD;
return (((halfn * halfn) % MOD) * base) % MOD;
}
vector<ll> inv(501,-1);
ll inverse(ll n){
if (inv[n] != -1) return inv[n];
return inv[n] = power(n, MOD-2);
}
ll add(ll a, ll b){
return (a+b) % MOD;
}
ll mul(ll a, ll b){
a %= MOD;
return (a*b) % MOD;
}
ll gcd(ll a, ll b){
if (a == 1) return 1;
if (a == 0) return b;
return gcd(b%a, a);
}
vector<ll> cnt[1000];
// cnt[i][j] = # solution for first ith school with last student sent is in ith compartment from left, and there are j students in the compartment
void solve(){
int n; cin >> n;
vector<ll> a(n), b(n); FOR(i,0,n) cin >> a[i] >> b[i];
vector<pair<ll,int>> pos;
FOR(i,0,n){
b[i]++;
pos.pb({a[i], i});
pos.pb({b[i], i});
}
sort(pos.begin(), pos.end());
vi l(n,-1), r(n,-1);
FOR(i,0,2*n){
int j = pos[i].se;
if (l[j] == -1) l[j] = i;
else r[j] = i;
}
FOR(i,0,2*n-1){
cnt[i].pb(0);
}
FOR(i,0,n){
ll total = 1;
FOR(j,0,l[i]){
for (ll val2 : cnt[j]){
total += val2;
total %= MOD;
}
}
//compartment from l[i] to r[i]
ll val[i+2];
FOR(j,0,r[i]-l[i]){
val[0] = 0;
ll interval = pos[j+l[i]+1].fi - pos[j+l[i]].fi;
val[1] = mul(interval,total);
for (ll val2 : cnt[j+l[i]]){
total += val2;
total %= MOD;
}
FOR(k,2,i+2){
ll new_val = 0;
if (cnt[j+l[i]].size()>=k) new_val = cnt[j+l[i]][k-1];
ll binom = mul(interval - k + 1, inverse(k)) ; //
new_val = mul(new_val, binom);
val[k] = new_val;
}
FOR(k,1,i+2){
if (k>=cnt[j+l[i]].size()){
cnt[j+l[i]].pb(val[k]);
continue;
}
cnt[j+l[i]][k] = (cnt[j+l[i]][k] + val[k]) % MOD;
}
}
}
ll ans = 0;
FOR(i,0,2*n-1){
for (ll val2 : cnt[i]){
ans = add(ans, val2);
}
}
cout << ans;
}
int main() {
ios::sync_with_stdio(false);
if (fopen("input.txt", "r")) {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
int TC = 1;
//cin >> TC;
FOR(i, 1, TC+1){
//cout << "Case #" << i << ": ";
solve();
}
}
Compilation message
boat.cpp:10: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
10 | #pragma GCC optimization ("Ofast")
|
boat.cpp:11: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
11 | #pragma GCC optimization ("unroll-loops")
|
boat.cpp: In function 'void solve()':
boat.cpp:99:39: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
99 | if (cnt[j+l[i]].size()>=k) new_val = cnt[j+l[i]][k-1];
| ~~~~~~~~~~~~~~~~~~^~~
boat.cpp:105:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
105 | if (k>=cnt[j+l[i]].size()){
| ~^~~~~~~~~~~~~~~~~~~~
boat.cpp: In function 'int main()':
boat.cpp:125:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
125 | freopen("input.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
boat.cpp:126:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
126 | freopen("output.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
56 ms |
1620 KB |
Output is correct |
2 |
Correct |
57 ms |
1640 KB |
Output is correct |
3 |
Correct |
57 ms |
1612 KB |
Output is correct |
4 |
Correct |
57 ms |
1664 KB |
Output is correct |
5 |
Correct |
59 ms |
1612 KB |
Output is correct |
6 |
Correct |
111 ms |
1668 KB |
Output is correct |
7 |
Correct |
101 ms |
1604 KB |
Output is correct |
8 |
Correct |
100 ms |
1720 KB |
Output is correct |
9 |
Correct |
107 ms |
1600 KB |
Output is correct |
10 |
Correct |
106 ms |
1616 KB |
Output is correct |
11 |
Correct |
104 ms |
1740 KB |
Output is correct |
12 |
Correct |
102 ms |
1720 KB |
Output is correct |
13 |
Correct |
104 ms |
1688 KB |
Output is correct |
14 |
Correct |
110 ms |
1720 KB |
Output is correct |
15 |
Correct |
107 ms |
1700 KB |
Output is correct |
16 |
Correct |
190 ms |
3640 KB |
Output is correct |
17 |
Correct |
190 ms |
3460 KB |
Output is correct |
18 |
Correct |
181 ms |
3532 KB |
Output is correct |
19 |
Correct |
183 ms |
3532 KB |
Output is correct |
20 |
Correct |
194 ms |
3480 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
56 ms |
1620 KB |
Output is correct |
2 |
Correct |
57 ms |
1640 KB |
Output is correct |
3 |
Correct |
57 ms |
1612 KB |
Output is correct |
4 |
Correct |
57 ms |
1664 KB |
Output is correct |
5 |
Correct |
59 ms |
1612 KB |
Output is correct |
6 |
Correct |
111 ms |
1668 KB |
Output is correct |
7 |
Correct |
101 ms |
1604 KB |
Output is correct |
8 |
Correct |
100 ms |
1720 KB |
Output is correct |
9 |
Correct |
107 ms |
1600 KB |
Output is correct |
10 |
Correct |
106 ms |
1616 KB |
Output is correct |
11 |
Correct |
104 ms |
1740 KB |
Output is correct |
12 |
Correct |
102 ms |
1720 KB |
Output is correct |
13 |
Correct |
104 ms |
1688 KB |
Output is correct |
14 |
Correct |
110 ms |
1720 KB |
Output is correct |
15 |
Correct |
107 ms |
1700 KB |
Output is correct |
16 |
Correct |
190 ms |
3640 KB |
Output is correct |
17 |
Correct |
190 ms |
3460 KB |
Output is correct |
18 |
Correct |
181 ms |
3532 KB |
Output is correct |
19 |
Correct |
183 ms |
3532 KB |
Output is correct |
20 |
Correct |
194 ms |
3480 KB |
Output is correct |
21 |
Correct |
1556 ms |
4536 KB |
Output is correct |
22 |
Correct |
1454 ms |
4576 KB |
Output is correct |
23 |
Correct |
1418 ms |
4572 KB |
Output is correct |
24 |
Correct |
1471 ms |
4500 KB |
Output is correct |
25 |
Correct |
1416 ms |
4616 KB |
Output is correct |
26 |
Execution timed out |
2012 ms |
4008 KB |
Time limit exceeded |
27 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
14 ms |
468 KB |
Output is correct |
2 |
Correct |
12 ms |
560 KB |
Output is correct |
3 |
Correct |
13 ms |
468 KB |
Output is correct |
4 |
Correct |
14 ms |
520 KB |
Output is correct |
5 |
Correct |
15 ms |
692 KB |
Output is correct |
6 |
Correct |
19 ms |
552 KB |
Output is correct |
7 |
Correct |
19 ms |
568 KB |
Output is correct |
8 |
Correct |
20 ms |
540 KB |
Output is correct |
9 |
Correct |
20 ms |
572 KB |
Output is correct |
10 |
Correct |
20 ms |
568 KB |
Output is correct |
11 |
Correct |
13 ms |
556 KB |
Output is correct |
12 |
Correct |
11 ms |
468 KB |
Output is correct |
13 |
Correct |
11 ms |
552 KB |
Output is correct |
14 |
Correct |
11 ms |
480 KB |
Output is correct |
15 |
Correct |
13 ms |
564 KB |
Output is correct |
16 |
Correct |
13 ms |
468 KB |
Output is correct |
17 |
Correct |
12 ms |
572 KB |
Output is correct |
18 |
Correct |
13 ms |
576 KB |
Output is correct |
19 |
Correct |
13 ms |
556 KB |
Output is correct |
20 |
Correct |
14 ms |
468 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
56 ms |
1620 KB |
Output is correct |
2 |
Correct |
57 ms |
1640 KB |
Output is correct |
3 |
Correct |
57 ms |
1612 KB |
Output is correct |
4 |
Correct |
57 ms |
1664 KB |
Output is correct |
5 |
Correct |
59 ms |
1612 KB |
Output is correct |
6 |
Correct |
111 ms |
1668 KB |
Output is correct |
7 |
Correct |
101 ms |
1604 KB |
Output is correct |
8 |
Correct |
100 ms |
1720 KB |
Output is correct |
9 |
Correct |
107 ms |
1600 KB |
Output is correct |
10 |
Correct |
106 ms |
1616 KB |
Output is correct |
11 |
Correct |
104 ms |
1740 KB |
Output is correct |
12 |
Correct |
102 ms |
1720 KB |
Output is correct |
13 |
Correct |
104 ms |
1688 KB |
Output is correct |
14 |
Correct |
110 ms |
1720 KB |
Output is correct |
15 |
Correct |
107 ms |
1700 KB |
Output is correct |
16 |
Correct |
190 ms |
3640 KB |
Output is correct |
17 |
Correct |
190 ms |
3460 KB |
Output is correct |
18 |
Correct |
181 ms |
3532 KB |
Output is correct |
19 |
Correct |
183 ms |
3532 KB |
Output is correct |
20 |
Correct |
194 ms |
3480 KB |
Output is correct |
21 |
Correct |
1556 ms |
4536 KB |
Output is correct |
22 |
Correct |
1454 ms |
4576 KB |
Output is correct |
23 |
Correct |
1418 ms |
4572 KB |
Output is correct |
24 |
Correct |
1471 ms |
4500 KB |
Output is correct |
25 |
Correct |
1416 ms |
4616 KB |
Output is correct |
26 |
Execution timed out |
2012 ms |
4008 KB |
Time limit exceeded |
27 |
Halted |
0 ms |
0 KB |
- |