Submission #447747

#	Time	Username	Problem	Language	Result	Execution time	Memory
447747		rainboy	Aliens (IOI07_aliens)	C11	100 / 100	3 ms	200 KiB

aliens

#include <stdio.h>

int query(long long x, long long y) {
	static char s[8];

	printf("examine %lld %lld\n", x, y), fflush(stdout);
	scanf("%s", s);
	return s[0] == 't';
}

int main() {
	long long n, x, y, di, dj, lower, upper, k, s, x_, y_;

	scanf("%lld%lld%lld", &n, &x, &y);
	lower = 0, upper = 1;
	while (x - upper >= 1 && query(x - upper, y))
		lower = upper, upper *= 2;
	while (upper - lower > 1) {
		k = (lower + upper) / 2;
		if (x - k >= 1 && query(x - k, y))
			lower = k;
		else
			upper = k;
	}
	x_ = lower;
	lower = 0, upper = 1;
	while (x + upper <= n && query(x + upper, y))
		lower = upper, upper *= 2;
	while (upper - lower > 1) {
		k = (lower + upper) / 2;
		if (x + k <= n && query(x + k, y))
			lower = k;
		else
			upper = k;
	}
	s = x_ + 1 + lower;
	lower = 0, upper = 1;
	while (y - upper >= 1 && query(x, y - upper))
		lower = upper, upper *= 2;
	while (upper - lower > 1) {
		k = (lower + upper) / 2;
		if (y - k >= 1 && query(x, y - k))
			lower = k;
		else
			upper = k;
	}
	y_ = lower;
	x += s / 2 - x_, y += s / 2 - y_;
	x_ = y_ = 0;
	for (di = -4; di <= 4; di++)
		for (dj = -4; dj <= 4; dj++)
			if ((di + dj) % 2 == 0) {
				long long x1 = x + s * di, y1 = y + s * dj;

				if (x1 >= 1 && x1 <= n && y1 >= 1 && y1 <= n && query(x1, y1))
					x_ += x1, y_ += y1;
			}
	x_ /= 13, y_ /= 13;
	printf("solution %lld %lld\n", x_, y_);
	return 0;
}

Compilation message (stderr)

aliens.c: In function 'query':
aliens.c:7:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |  scanf("%s", s);
      |  ^~~~~~~~~~~~~~
aliens.c: In function 'main':
aliens.c:14:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |  scanf("%lld%lld%lld", &n, &x, &y);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10