Submission #1058860

#	Time	Username	Problem	Language	Result	Execution time	Memory
1058860		rainboy	COVID tests (CEOI24_covid)	C11	100 / 100	1323 ms	11860 KiB

Main

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

#define N	1000
#define INF	1e9

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

unsigned int Z = 12345;

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

int n, m; double p;

int query(int l, int r) {
	static char cc[N + 1], s[2];

	memset(cc, '0', n * sizeof *cc), memset(cc + l, '1', (r - l) * sizeof *cc);
	printf("Q %s\n", cc), fflush(stdout);
	scanf("%s", s);
	return s[0] == 'P';
}

double qq[N + 1], dp[N + 1], dq[N + 1][N + 1]; int ll[N + 1], mm[N + 1][N + 1];

void init() {
	int i, l, r, m;
	double x;

	qq[0] = 1;
	for (i = 1; i <= n; i++)
		qq[i] = qq[i - 1] * (1 - p);
	dp[0] = 0;
	for (r = 1; r <= n; r++) {
		dp[r] = INF;
		for (l = r - 1; l >= 0 && l >= r - n / 2; l--) {
			if (r - l == 1)
				dq[l][r] = dp[l];
			else {
				dq[l][r] = INF;
				for (m = r - 1; m > l; m--) {
					x = (dq[l][m] * qq[r - m] * (1 - qq[m - l]) + dq[m][r] * (1 - qq[r - l] - qq[r - m] * (1 - qq[m - l]))) / (1 - qq[r - l]) + 1;
					if (dq[l][r] > x)
						dq[l][r] = x, mm[l][r] = m;
				}
			}
			x = dp[l] * qq[r - l] + dq[l][r] * (1 - qq[r - l]) + 1;
			if (dp[r] > x)
				dp[r] = x, ll[r] = l;
		}
	}
}

char cc[N + 1];

void solve(int r);

void solve_(int l, int r) {
	if (r - l == 1)
		cc[l] = '1', solve(l);
	else if (query(mm[l][r], r))
		solve_(mm[l][r], r);
	else
		solve_(l, mm[l][r]);
}

void solve(int r) {
	if (r == 0)
		return;
	else if (query(ll[r], r))
		solve_(ll[r], r);
	else
		solve(ll[r]);
}

int main() {
	int t, subtask;

	scanf("%d%lf%d", &n, &p, &t), m = 1 / p * 4, subtask = t == 1 ? 1 : 2, init();
	while (t--) {
		int i;

		memset(cc, '0', n * sizeof *cc), cc[n] = 0;
		if (subtask == 1) {
			for (i = 0; i < n; i++)
				if (query(i, i + 1))
					cc[i] = '1';
		} else
			solve(n);
		printf("A %s\n", cc), fflush(stdout);
		scanf("%*s");
	}
	return 0;
}

Compilation message (stderr)

Main.c: In function 'query':
Main.c:22:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |  scanf("%s", s);
      |  ^~~~~~~~~~~~~~
Main.c: In function 'main':
Main.c:81:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |  scanf("%d%lf%d", &n, &p, &t), m = 1 / p * 4, subtask = t == 1 ? 1 : 2, init();
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.c:93:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |   scanf("%*s");
      |   ^~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 90 / 90