Submission #1014951

#	Time	Username	Problem	Language	Result	Execution time	Memory
1014951		rainboy	Tiles (BOI24_tiles)	C11	100 / 100	170 ms	23480 KiB

Main

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

#define N	200000
#define N_	(1 << 18)	/* N_ = pow2(ceil(log2(N))) */

int max(int a, int b) { return a > b ? a : b; }

unsigned int Z = 12345;

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

int xx[N], yy[N], n;

int compare_y(int i, int j) {
	return yy[i] - yy[j];
}

int compare_xy(int i, int j) {
	return xx[i] != xx[j] ? xx[i] - xx[j] : yy[i] - yy[j];
}

int (*compare)(int, int);

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) {
			int c = compare(ii[j], i_);

			if (c == 0)
				j++;
			else if (c < 0) {
				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 yy1[N], n1;

int sz[N_ * 2];
int ss1[N_ * 2], ss2[N_ * 2];
int ccp[N_ * 2], ssp[N_ * 2];
int ccq[N_ * 2], ssq[N_ * 2];
char good[N_ * 2]; char lz[N_];
int h_, n_;

int flip(int c) {
	return c == 0 ? 0 : (c < 0 ? (c == -1 ? -2 : -1) : (c == 1 ? 2 : 1));
}

void put(int i, int x) {
	int tmp;

	if (x == -1) {
		tmp = ss1[i], ss1[i] = ss2[i], ss2[i] = tmp;
		ccp[i] = flip(ccp[i]), ccq[i] = flip(ccq[i]);
		if (i < n_)
			lz[i] = flip(lz[i]);
	} else if (x != -2) {
		if (x == 0)
			ss1[i] = ss2[i] = 0;
		else if (x == 1)
			ss1[i] = sz[i], ss2[i] = 0;
		else
			ss1[i] = 0, ss2[i] = sz[i];
		ccp[i] = ccq[i] = x, ssp[i] = ssq[i] = x == 0 ? 0 : sz[i];
		good[i] = 1;
		if (i < n_)
			lz[i] = x;
	}
}

void pus(int i) {
	if (lz[i] != -2)
		put(i << 1 | 0, lz[i]), put(i << 1 | 1, lz[i]), lz[i] = -2;
}

void pul(int i) {
	if (lz[i] == -2) {
		int l = i << 1, r = l | 1;

		ss1[i] = ss1[l] + ss1[r], ss2[i] = ss2[l] + ss2[r];
		ccp[i] = ccp[l];
		if (ccp[l] == 0)
			ssp[i] = 0;
		else
			ssp[i] = ssp[l] < sz[l] || ccp[r] != ccp[l] ? ssp[l] : sz[l] + ssp[r];
		ccq[i] = ccq[r];
		if (ccq[r] == 0)
			ssq[i] = 0;
		else
			ssq[i] = ssq[r] < sz[r] || ccq[l] != ccq[r] ? ssq[r] : ssq[l] + sz[r];
		good[i] = good[l] && good[r] && (ccq[l] != ccp[r] ? (ssq[l] == sz[l] || ssq[l] % 2 == 0) && (ssp[r] == sz[r] || ssp[r] % 2 == 0) : ssq[l] == sz[l] || ssp[r] == sz[r] || (ssq[l] + ssp[r]) % 2 == 0);
	}
}

void push(int i) {
	int h;

	for (h = h_; h > 0; h--)
		pus(i >> h);
}

void pull(int i) {
	while (i > 1)
		pul(i >>= 1);
}

void build() {
	int i;

	h_ = 0;
	while (1 << h_ < n1)
		h_++;
	n_ = 1 << h_;
	memset(lz, -2, n_ * sizeof *lz);
	memset(good, 1, n_ * 2 * sizeof *good);
	for (i = 0; i < n1; i++)
		sz[n_ + i] = i + 1 < n1 ? yy1[i + 1] - yy1[i] : 1;
	for (i = n_ - 1; i > 0; i--)
		sz[i] = sz[i << 1 | 0] + sz[i << 1 | 1], pul(i);
}

void update(int l, int r, int x) {
	int l_ = l += n_, r_ = r += n_;

	push(l_), push(r_);
	for ( ; l <= r; l >>= 1, r >>= 1) {
		if ((l & 1) == 1)
			put(l++, x);
		if ((r & 1) == 0)
			put(r--, x);
	}
	pull(l_), pull(r_);
}

int query(int l, int r) {
	int s, s1, s2;

	push(l += n_), push(r += n_);
	s = 0, s1 = s2 = 0;
	for ( ; l <= r; l >>= 1, r >>= 1) {
		if ((l & 1) == 1)
			s += sz[l], s1 += ss1[l], s2 += ss2[l], l++;
		if ((r & 1) == 0)
			s += sz[r], s1 += ss1[r], s2 += ss2[r], r--;
	}
	return s1 == 0 && s2 == 0 ? 1 : (s1 == s ? 0 : -1);
}

int main() {
	static int ii[N], xx_[N], yy_[N];
	int i, j, x1, x2, y, y1, y2, ans, t;

	scanf("%d%*d", &n);
	for (i = 0; i < n; i++)
		scanf("%d%d", &xx[i], &yy[i]);
	n1 = 0;
	for (i = 0; i < n; i++)
		if ((xx[i] != xx[(i + 1) % n]) != (xx[i] != xx[(i - 1 + n) % n]))
			xx_[n1] = xx[i], yy_[n1] = yy[i], n1++;
	memcpy(xx, xx_, n1 * sizeof *xx_), memcpy(yy, yy_, n1 * sizeof *yy_), n = n1;
	for (i = 0; i < n; i++)
		ii[i] = i;
	compare = compare_y, sort(ii, 0, n);
	n1 = 0;
	for (i = 0; i < n; i = j) {
		j = i, y = yy[ii[i]];
		while (j < n && yy[ii[j]] == y)
			yy[ii[j++]] = n1;
		yy1[n1++] = y;
	}
	build();
	compare = compare_xy, sort(ii, 0, n);
	ans = 0;
	for (i = 0; i + 1 < n; i += 2) {
		y1 = yy[ii[i]], y2 = yy[ii[i + 1]];
		t = query(y1, y2 - 1);
		if (t == -1)
			break;
		update(y1, y2 - 1, t);
		if (i + 2 < n && xx[ii[i + 2]] != xx[ii[i + 1]]) {
			if (!good[1] || ssp[1] % 2 != 0 || ssq[1] % 2 != 0)
				break;
			x1 = xx[ii[i + 1]], x2 = xx[ii[i + 2]];
			if (ss2[1] == 0)
				ans = max(ans, x1 + (x2 - x1) / 2 * 2);
			if (ss1[1] == 0)
				ans = max(ans, x1 + 1 + (x2 - x1 - 1) / 2 * 2);
			if ((x2 - x1) % 2 != 0)
				put(1, -1);
		}
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'main':
Main.c:166:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  166 |  scanf("%d%*d", &n);
      |  ^~~~~~~~~~~~~~~~~~
Main.c:168:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  168 |   scanf("%d%d", &xx[i], &yy[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 9 / 9
• Subtask 3: 11 / 11
• Subtask 4: 19 / 19
• Subtask 5: 22 / 22
• Subtask 6: 25 / 25
• Subtask 7: 10 / 10