Submission #709835

#	Time	Username	Problem	Language	Result	Execution time	Memory
709835		rainboy	Let's Win the Election (JOI22_ho_t3)	C11	100 / 100	186 ms	340 KiB

Main

#include <stdio.h>
#include <string.h>

#define N	500
#define INF	0x3f3f3f3f

double min(double a, double b) { return a < b ? a : b; }

unsigned int X = 12345;

int rand_() {
	return (X *= 3) >> 1;
}

int aa[N], bb[N];

void sort(int *ii, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;

		while (j < k)
			if (bb[ii[j]] == bb[i_])
				j++;
			else if (bb[ii[j]] < bb[i_]) {
				tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
			}
		sort(ii, l, i);
		l = k;
	}
}

int main() {
	static int ii[N];
	static char cc[N], cc_[N];
	int n, k, l, l_, h, i, i_, i1, j;
	double x, x_, d, d_, d1, ans;

	scanf("%d%d", &n, &k);
	for (i = 0; i < n; i++) {
		scanf("%d%d", &aa[i], &bb[i]);
		if (bb[i] == -1)
			bb[i] = INF;
	}
	for (i = 0; i < n; i++)
		ii[i] = i;
	sort(ii, 0, n);
	ans = INF;
	x = 0;
	for (l = 0; l <= k && (l == 0 || bb[ii[l - 1]] != INF); l++) {
		if (l > 0)
			cc[l - 1] = 1, x += (double) bb[ii[l - 1]] / l;
		memcpy(cc_, cc, n * sizeof *cc);
		x_ = x;
		for (h = l; h < k; h++) {
			for (j = 0; j < n; j++)
				if (cc_[j] == 0)
					break;
			d = (double) bb[ii[j]] / l, d1 = INF, i1 = -1;
			for (i = n - 1, l_ = l; i >= 0; i--) {
				i_ = ii[i];
				if (cc_[i] == 0) {
					if (d1 > (d_ = (double) aa[i_] / (l + 1)))
						d1 = d_, i1 = i;
				} else if (cc_[i] == 1) {
					if (d1 > (d_ = (double) aa[i_] / (l + 1) - (double) bb[i_] / l_ + d))
						d1 = d_, i1 = i;
					if (l_ > 1)
						d += (double) bb[i_] / (l_ - 1) - (double) bb[i_] / l_, l_--;
				}
			}
			x_ += d1;
			if (cc_[i1] == 0)
				cc_[i1] = -1;
			else
				cc_[i1] = -1, cc_[j] = 1;
		}
		ans = min(ans, x_);
	}
	printf("%f\n", ans);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'main':
Main.c:42:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~
Main.c:44:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |   scanf("%d%d", &aa[i], &bb[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 11 / 11
• Subtask 4: 12 / 12
• Subtask 5: 33 / 33
• Subtask 6: 11 / 11
• Subtask 7: 23 / 23