Submission #450401

#	Time	Username	Problem	Language	Result	Execution time	Memory
450401		nonsensenonsense1	Worm Worries (BOI18_worm)	C++17	0 / 100	1 ms	200 KiB

worm

#include <cstdio>
#include <cassert>

int n, m, k, q;

int query(int x) 
{
	printf("? %d 1 1\n", x);
	fflush(stdout);
	scanf("%d", &x);
	return x;
}

int main() 
{
	scanf("%d%d%d%d", &n, &m, &k, &q);
	int l = 1, r = n, x = -1, xval, y = -1, yval;
	while (l < r) {
		if (x == -1 || x < l || x >= (8 * l + 13 * r - 1) / 21 + 1) {
			x = (13 * l + 8 * r) / 21;
			xval = query(x);
		}
		if (y == -1 || y > r || y <= x) {
			y = (8 * l + 13 * r - 1) / 21 + 1;
			yval = query(y);
		}
		assert(x < y);
		assert(x >= l);
		assert(y <= r);
		if (xval > yval) {
			r = y - 1;
			y = x;
			yval = xval;
			x = -1;
		}
		else {
			l = x + 1;
			x = y;
			xval = yval;
			y = -1;
		}
	}
	printf("! %d\n", l);
	return 0;
}

Compilation message (stderr)

worm.cpp: In function 'int query(int)':
worm.cpp:10:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |  scanf("%d", &x);
      |  ~~~~~^~~~~~~~~~
worm.cpp: In function 'int main()':
worm.cpp:16:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |  scanf("%d%d%d%d", &n, &m, &k, &q);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
worm.cpp:30:3: warning: 'yval' may be used uninitialized in this function [-Wmaybe-uninitialized]
   30 |   if (xval > yval) {
      |   ^~
worm.cpp:30:3: warning: 'xval' may be used uninitialized in this function [-Wmaybe-uninitialized]

• Subtask 1: 0 / 10
• Subtask 2: 0 / 22
• Subtask 3: 0 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 14
• Subtask 6: 0 / 23