Submission #309997

#	Time	Username	Problem	Language	Result	Execution time	Memory
309997		ttnhuy313	Mountains (IOI17_mountains)	C++14	0 / 100	1 ms	384 KiB

mountains

#include <bits/stdc++.h>
 
using namespace std;
#define int long long
#define sqr(a) (a * a)
typedef pair <int, int> ii;
 
const int N = 2005;
int dp[N][N];
 
int cross(ii a, ii b) {
	return a.first * b.second - a.second * b.first;
}
 
bool ccw(ii a, ii b, ii c) {
	return cross(ii(b.first - a.first, b.second - a.second), ii(c.first - a.first, c.second - a.second)) > 0;
}
 
int maximum_deevs(vector <int32_t> y) {
	int n = y.size();
	for (int r = 0; r < n; ++r) {
		dp[r][r] = 1;
		if (r == 0) continue;
		dp[r - 1][r] = 1;
		int xx = 1, yy = y[r] - y[r - 1], sum = 0, lastSeen = r - 1, id = r - 1;
		for (int l = r - 2; l >= 0; --l) {
			int curx = r - l, cury = y[r] - y[l];
			if (sqr(curx) * (sqr(xx) + sqr(yy)) < sqr(xx) * (sqr(curx) + sqr(cury))) {
				xx = curx;
				yy = cury;
				id = l;
			}
			if (ccw(ii(r, y[r]), ii(id, y[id]), ii(l, y[l]))) { // cross the mountain
				dp[l][r] = sum + dp[l][lastSeen - 1] + 1;
			} else {
				sum += dp[l + 1][lastSeen - 1];
				lastSeen = l;
			}
			dp[l][r] = max(dp[l][r], dp[l][r - 1]);
		}
	}
 
	return dp[0][n - 1];
}

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 30
• Subtask 4: 0 / 30