Submission #249125

#	Time	Username	Problem	Language	Result	Execution time	Memory
249125		sahil_k	Boat (APIO16_boat)	C++14	0 / 100	4 ms	4224 KiB

boat

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
#define MOD 1000000007
int n;
int s_val[510], e_val[510];
vector<int> pts;
int s_id[510], e_id[510];
long long dp[510][1010]; // No. of ways to send exactly j boats from i.
long long ttl;
int main () {
	cin >> n;
	for (int i=0; i<n; i++) {
		cin >> s_val[i] >> e_val[i];
		pts.push_back(s_val[i]);
		pts.push_back(e_val[i]);
	}
	pts.push_back(0);
	sort(pts.begin(), pts.end());
	pts.resize(unique(pts.begin(), pts.end())-pts.begin());
	for (int i=0; i<n; i++) {
		s_id[i+1] = lower_bound(pts.begin(), pts.end(), s_val[i])-pts.begin();
		e_id[i+1] = lower_bound(pts.begin(), pts.end(), e_val[i])-pts.begin();
	}
	int m = pts.size();
	dp[0][0] = 1;
	for (int i=1; i<=n; i++) {
		ttl = 0;
		dp[i][0] = 1;
		for (int j=1; j<m; j++) {
			dp[i][j] = dp[i-1][j];
			ttl = (ttl+dp[i-1][j-1]*(pts[j]-pts[j-1]))%MOD;
			if (s_id[i] <= j && j <= e_id[i]) dp[i][j] = (dp[i][j]+ttl)%MOD;
		}
	}
	long long o = 0;
	for (int j=1; j<m-1; j++) {
		o = (o+dp[n][j]*(pts[j+1]-pts[j]))%MOD;
	}
	o = (o+dp[n][m-1])%MOD;
	cout << o << endl;
}

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