Submission #776316

#	Time	Username	Problem	Language	Result	Execution time	Memory
776316		rainboy	Good Game (CCO22_day2problem3)	C11	25 / 25	173 ms	11528 KiB

Main

#include <stdio.h>

#define N	1000000

int check(char *cc, int n) {
	int i, j, d;

	if (n == 0)
		return 1;
	d = 2;
	for (i = 0; i + 1 < n; i++)
		if (cc[i] != cc[i + 1])
			d++;
	if (d == n + 1)
		return 0;
	for (i = 0; i < n; i = j) {
		j = i + 1;
		while (j < n && cc[j] != cc[j - 1])
			j++;
		if (j - i > (d + 1) / 2)
			return 0;
	}
	if (d % 2 == 0)
		return 1;
	i = 0;
	while (i + 1 < n && cc[i] != cc[i + 1])
		i++;
	if (i == n - 1)
		return 0;
	j = n - 1;
	while (j > 0 && cc[j] != cc[j - 1])
		j--;
	if (j == 0)
		return 0;
	return (i + 1) + (n - j) <= d / 2 + 1;
}

int ii[N], ll[N], m;

void remove_(int i, int l) {
	while (l > 0)
		if (l % 2 != 0)
			ii[m] = i, ll[m] = 3, m++, l -= 3;
		else
			ii[m] = i, ll[m] = 2, m++, l -= 2;
}

int solve(char *cc, int n, int t, int print) {
	static char cc_[N + 1];
	int n_, nl, nr, h, i, i_, j, j_, d, d_;

	d = 2;
	for (i = 0; i + 1 < n; i++)
		if (cc[i] != cc[i + 1])
			d++;
	n_ = 0, d_ = 0, m = 0;
	for (i = 0; i <= n; i++) {
		if (i == n || n_ > 0 && cc[i] != cc_[n_ - 1])
			if (n_ >= 2 && cc_[n_ - 2] == cc_[n_ - 1] && (d % 2 != 0 || d_ > 1 && i < n) && t > 0) {
				i_ = n_ - 3;
				while (i_ >= 0 && cc_[i_] == cc_[n_ - 1])
					i_--;
				i_++;
				if (print)
					remove_(i_, n_ - i_);
				n_ = i_;
				t--;
				if (--d_ == 0 || i == n)
					d--;
			}
		if (i < n) {
			if (n_ == 0 || cc_[n_ - 1] != cc[i])
				d_++;
			cc_[n_++] = cc[i];
		}
	}
	if (print) {
		d = 2;
		for (i = 0; i + 1 < n_; i++)
			if (cc_[i] != cc_[i + 1])
				d++;
		i_ = j_ = -1;
		for (i = 0; i < n_; i = j) {
			j = i + 1;
			while (j < n_ && cc_[j] != cc_[j - 1])
				j++;
			if (j - i == (d + 1) / 2) {
				i_ = i, j_ = j - 1;
				break;
			}
		}
		nr = 0;
		for (i = j_ + 1; i < n_; i = j) {
			j = i + 1;
			while (j < n_ && cc_[j] == cc_[i])
				j++;
			if (j < n_)
				remove_(j_--, j - i + 1);
			else
				nr = j - i;
		}
		nl = 0;
		for (j = i_ - 1; j >= 0; j = i) {
			i = j - 1;
			while (i >= 0 && cc_[i] == cc_[j])
				i--;
			if (i >= 0)
				remove_(i + 1, j - i + 1);
			else
				nl = j - i;
		}
		if (d % 2 == 0)
			remove_(0, nl + nr + 1);
		else
			remove_(0, nl + 1), remove_(0, nr + 1);
		printf("%d\n", m);
		for (h = 0; h < m; h++)
			printf("%d %d\n", ii[h] + 1, ll[h]);
	}
	return check(cc_, n_);
}

int main() {
	static char cc[N + 1];
	int n, t, lower, upper;

	scanf("%d%s", &n, cc);
	if (!check(cc, n)) {
		printf("-1\n");
		return 0;
	}
	lower = 0, upper = n + 1;
	while (upper - lower > 1) {
		t = (lower + upper) / 2;
		if (solve(cc, n, t, 0))
			lower = t;
		else
			upper = t;
	}
	solve(cc, n, lower, 1);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'solve':
Main.c:58:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   58 |   if (i == n || n_ > 0 && cc[i] != cc_[n_ - 1])
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
Main.c:59:71: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   59 |    if (n_ >= 2 && cc_[n_ - 2] == cc_[n_ - 1] && (d % 2 != 0 || d_ > 1 && i < n) && t > 0) {
      |                                                                ~~~~~~~^~~~~~~~
Main.c: In function 'main':
Main.c:127:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |  scanf("%d%s", &n, cc);
      |  ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 3 / 3
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 9 / 9