Submission #703255

#	Time	Username	Problem	Language	Result	Execution time	Memory
703255		rainboy	T-Covering (eJOI19_covering)	C11	100 / 100	111 ms	32772 KiB

covering

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

#define NM	1000000
#define INF	0x3f3f3f3f

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

int di[] = { -1, 1, 0, 0 };
int dj[] = { 0, 0, -1, 1 };

int ds[NM], vv[NM], ee[NM], ww[NM];

int find(int i) {
	return ds[i] < 0 ? i : (ds[i] = find(ds[i]));
}

void join(int i, int j) {
	i = find(i);
	j = find(j);
	if (i == j) {
		ee[i]++;
		return;
	}
	if (ds[i] > ds[j])
		ds[i] = j, vv[j] += vv[i], ee[j] += ee[i] + 1, ww[j] = min(ww[j], ww[i]);
	else {
		if (ds[i] == ds[j])
			ds[i]--;
		ds[j] = i, vv[i] += vv[j], ee[i] += ee[j] + 1, ww[i] = min(ww[i], ww[j]);
	}
}

int main() {
	static int aa[NM], ej[NM][2], eo[NM];
	static char special[NM];
	int n, m, nm, k, h, i, j, ij;
	long long ans;

	scanf("%d%d", &n, &m), nm = n * m;
	for (i = 0; i < nm; i++)
		scanf("%d", &aa[i]);
	scanf("%d", &k);
	memset(ww, 0x3f, nm * sizeof *ww);
	ans = 0;
	while (k--) {
		scanf("%d%d", &i, &j), ij = i * m + j;
		ans += aa[ij];
		special[ij] = 1;
		aa[ij] = -INF;
	}
	for (ij = 0; ij < nm; ij++)
		if (special[ij]) {
			i = ij / m, j = ij % m;
			for (h = 0; h < 4; h++) {
				int i_ = i + di[h], j_ = j + dj[h], ij_ = i_ * m + j_;

				if (i_ >= 0 && i_ < n && j_ >= 0 && j_ < m) {
					if (eo[ij_] == 2) {
						printf("No\n");
						return 0;
					}
					ej[ij_][eo[ij_]++] = ij;
					ans += aa[ij_];
					ww[ij] = min(ww[ij], aa[ij_]);
				} else {
					ans += -INF;
					ww[ij] = -INF;
				}
			}
		}
	memset(ds, -1, nm * sizeof *ds);
	for (i = 0; i < nm; i++)
		vv[i] = 1;
	for (i = 0; i < nm; i++)
		if (eo[i] == 2)
			join(ej[i][0], ej[i][1]), ans -= aa[i];
	for (i = 0; i < nm; i++)
		if (ds[i] < 0) {
			if (vv[i] < ee[i]) {
				printf("No\n");
				return 0;
			}
			if (vv[i] > ee[i] && ww[i] != INF)
				ans -= ww[i];
		}
	if (ans < 0) {
		printf("No\n");
		return 0;
	}
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

covering.c: In function 'main':
covering.c:40:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |  scanf("%d%d", &n, &m), nm = n * m;
      |  ^~~~~~~~~~~~~~~~~~~~~
covering.c:42:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~
covering.c:43:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |  scanf("%d", &k);
      |  ^~~~~~~~~~~~~~~
covering.c:47:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |   scanf("%d%d", &i, &j), ij = i * m + j;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 15 / 15
• Subtask 6: 20 / 20
• Subtask 7: 30 / 30