Submission #109371

#	Time	Username	Problem	Language	Result	Execution time	Memory
109371		b2563125	Boat (APIO16_boat)	C++14	58 / 100	2039 ms	14968 KiB

boat

#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define int long long
#define vel vector<long long>
#define V vector
#define ll long long
#define rep(i,n) for(int i=0;i<n;i++)
int pr = 1000000007;
void uni(vel &a) {
	vel ans(1, a[0]);
	int n = a.size();
	rep(i, n - 1) { if (a[i + 1] != a[i]) { ans.push_back(a[i + 1]); } }
	a = ans;
}
int rui(int a, int n) {
	if (n == 0) { return 1; }
	int back = rui(a, n / 2);
	back *= back; back %= pr;
	if (n % 2 == 0) { return back; }
	return (back*a) % pr;
}
int inv(int a) {
	return rui(a, pr - 2);
}
signed main() {
	ll n; cin >> n;
	vel a(n);
	vel b(n);
	vel all_time(1, 0);
	rep(i, n) {
		cin >> a[i] >> b[i]; b[i]++;
		all_time.push_back(a[i]);
		all_time.push_back(b[i]);
	}
	sort(all_time.begin(), all_time.end());
	uni(all_time);
	int sz = all_time.size();
	vel gap(sz - 1);
	rep(i, sz - 1) { gap[i] = all_time[i + 1] - all_time[i]; }
	vel count(sz - 1);
	rep(i, n) {
		a[i] = lower_bound(all_time.begin(), all_time.end(), a[i]) - all_time.begin();
		b[i] = lower_bound(all_time.begin(), all_time.end(), b[i]) - all_time.begin();
		rep(j, b[i] - a[i]) {
			count[a[i] + j]++;
		}
	}
	V<vel> com(sz - 1);
	rep(i, sz - 1) {
		int ba = 1;
		rep(j, count[i]) {
			ba *= gap[i] - j; ba %= pr;
			ba *= inv(j + 1); ba %= pr;
			com[i].push_back(ba);
		}
	}
	V<V<vel>> dp1(2, V<vel>(sz - 1, vel(n)));
	vel now_count(sz - 1, 0);
	rep(i, n) {
		int now = i % 2;
		int nex = (i + 1) % 2;
		dp1[nex] = dp1[now];
		int sum = 1;
		rep(j, a[i]) {
			rep(k, now_count[j]) {
				sum += dp1[now][j][k] * com[j][k];
				sum %= pr;
			}
		}
		for (int j = a[i]; j < b[i]; j++) {
			dp1[nex][j][0] += sum; dp1[nex][j][0] %= pr;
			rep(k, now_count[j]) {
				dp1[nex][j][k + 1] += dp1[now][j][k]; dp1[nex][j][k + 1] %= pr;
				sum += dp1[now][j][k] * com[j][k];
				sum %= pr;
			}
			now_count[j]++;
		}
	}
	ll ans = 0;
	rep(i, sz - 1) {
		rep(k, count[i]) {
			ans += dp1[n % 2][i][k] * com[i][k];
			ans %= pr;
		}
	}
	cout << ans << endl;
	return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 22 / 22
• Subtask 3: 27 / 27
• Subtask 4: 0 / 42