Submission #478886

#	Time	Username	Problem	Language	Result	Execution time	Memory
478886		rainboy	새로운 문제 (COCI19_akvizna)	C11	130 / 130	89 ms	1872 KiB

Main

#include <stdio.h>

#define N	100000

double dp[N + 1]; int kk[N + 1], n;

double cross(int i, int j, int k) {
	return (j - i) * (dp[k] - dp[i]) - (k - i) * (dp[j] - dp[i]);
}

double eval(int i, double x) {
	return -i * x + dp[i];
}

void solve(double c) {
	static int qu[N + 1];
	int i, head, cnt;

	dp[0] = 0, kk[0] = 0;
	head = cnt = 0;
	qu[head + cnt++] = 0;
	for (i = 1; i <= n; i++) {
		while (cnt >= 2 && eval(qu[head], (double) 1 / i) < eval(qu[head + 1], (double) 1 / i))
			head++, cnt--;
		dp[i] = eval(qu[head], (double) 1 / i) + 1 - c, kk[i] = kk[qu[head]] + 1;
		while (cnt >= 2 && cross(qu[head + cnt - 2], qu[head + cnt - 1], i) >= 0)
			cnt--;
		qu[head + cnt++] = i;
	}
}

int main() {
	int k, r;
	double lower, upper;

	scanf("%d%d", &n, &k);
	lower = 0, upper = 1;
	for (r = 0; r < 60; r++) {
		double c = (lower + upper) / 2;

		solve(c);
		if (kk[n] <= k)
			upper = c;
		else
			lower = c;
	}
	solve(upper);
	printf("%.9f\n", dp[n] + k * upper);
	return 0;
}

Compilation message (stderr)

akvizna.c: In function 'main':
akvizna.c:36:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~

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