Submission #905288

#	Time	Username	Problem	Language	Result	Execution time	Memory
905288		rainboy	Mountains (IOI17_mountains)	C++17	100 / 100	10 ms	16216 KiB

mountains

#include "mountains.h"
#include <vector>

using namespace std;

typedef vector<int> vi;

const int N = 2000;

int max(int a, int b) { return a > b ? a : b; }

long long cross(int x0, int y0, int x1, int y1, int x2, int y2) {
	return (long long) (x1 - x0) * (y2 - y0) - (long long) (x2 - x0) * (y1 - y0);
}

int dp[N][N];

int maximum_deevs(vi yy) {
	int n = yy.size();
	for (int i = n - 1; i >= 0; i--) {
		dp[i][i] = 1;
		int k = i, x = 0;
		for (int j = i + 1; j < n; j++) {
			dp[i][j] = dp[i + 1][j];
			if (cross(i, yy[i], k, yy[k], j, yy[j]) >= 0) {
				if (j - k > 1)
					x += dp[k + 1][j - 1];
				k = j;
				dp[i][j] = max(dp[i][j], x + 1);
			} else
				dp[i][j] = max(dp[i][j], x + dp[k + 1][j] + 1);
		}
	}
	return dp[0][n - 1];
}

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