Submission #501204

#	Time	Username	Problem	Language	Result	Execution time	Memory
501204		rainboy	Wells (CEOI21_wells)	C11	50 / 100	149 ms	2200 KiB

wells

#include <stdio.h>

#define N	10000
#define INF	0x3f3f3f3f3f3f3f3fLL
#define MD	1000000007

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

int mem[(N - 1) * 2], *ptr = mem, *ej[N], eo[N], n, k;

int ll[N], jj[N], ta[N], tb[N], kk[N + 1], qu[N * 2];

void dfs1(int p, int i, int d) {
	int o;

	kk[d + 1]++;
	ll[i] = 0, jj[i] = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs1(i, j, d + 1);
			if (ll[i] < ll[j])
				ll[i] = ll[j], jj[i] = j;
		}
	}
	ll[i]++;
}

void dfs2(int p, int i, int d) {
	static int time;
	int o;

	qu[ta[i] = time++] = i, tb[i] = kk[d]++;
	if (jj[i] != -1)
		dfs2(i, jj[i], d + 1);
	else
		time++;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p && j != jj[i])
			dfs2(i, j, d + 1);
	}
}

int cnt[N * 2]; long long xx[N + 1];

void get_range(int a, int *l, int *r) {
	*l = tb[qu[a]], *r = *l + cnt[a];
}

void dfs3(int p, int i) {
	int o, d, l1, r1, l2, r2;
	long long c;

	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			dfs3(i, j);
	}
	if (k <= ll[i]) {
		get_range(ta[i] + k - 1, &l1, &r1);
		xx[l1]++, xx[r1]--;
		if (p != -1)
			xx[tb[p]] -= r1 - l1, xx[tb[p] + 1] += r1 - l1;
	}
	cnt[ta[i]]++;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p && j != jj[i]) {
			for (d = 1; d <= ll[j] && d < k; d++)
				if (k - d <= ll[i]) {
					get_range(ta[i] + k - d - 1, &l1, &r1), get_range(ta[j] + d - 1, &l2, &r2);
					c = (long long) (r1 - l1) * (r2 - l2);
					xx[l1] += r2 - l2, xx[r1] -= r2 - l2;
					xx[l2] += r1 - l1, xx[r2] -= r1 - l1;
					xx[tb[i]] -= c, xx[tb[i] + 1] += c;
					if (p != -1)
						xx[tb[p]] -= c, xx[tb[p] + 1] += c;
				}
			for (d = 1; d <= ll[j]; d++)
				cnt[ta[i] + d] += cnt[ta[j] + d - 1];
		}
	}
}

long long ww[N];

void dfs4(int p, int i) {
	int o;

	ww[i] = xx[tb[i]];
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs4(i, j);
			ww[i] += ww[j];
		}
	}
}

long long dp[N * 2]; int dq[N * 2];

void update(int l, int r, long long p, int q) {
	int i;

	for (i = l; i <= r; i++)
		dp[i] += p, dq[i] = (long long) dq[i] * q % MD;
}

void query(int l, int r, long long *p_, int *q_) {
	int i;
	long long p;
	int q;

	p = INF, q = 0;
	for (i = l; i <= r; i++) {
		if (p > dp[i])
			p = dp[i], q = 0;
		if (p == dp[i])
			q = (q + dq[i]) % MD;
	}
	*p_ = p, *q_ = q;
}

void dfs5(int p, int i) {
	int o, j, di, dj, d;
	long long pi, pj, p_;
	int qi, qj, q;

	dp[ta[i] + 0] = ww[i], dq[ta[i] + 0] = 1;
	if (jj[i] == -1)
		dp[ta[i] + 1] = 0, dq[ta[i] + 1] = 1;
	else {
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (j != p)
				dfs5(i, j);
		}
		j = jj[i];
		query(ta[j], ta[j] + ll[j], &p_, &q);
		dp[ta[i] + 0] += p_, dq[ta[i] + 0] = q;
		if (ll[i] >= k)
			dp[ta[i] + k] = INF, dq[ta[i] + k] = 0;
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (j != p && j != jj[i]) {
				query(ta[j], ta[j] + ll[j], &p_, &q);
				dp[ta[i] + 0] += p_, dq[ta[i] + 0] = (long long) dq[ta[i] + 0] * q % MD;
				for (di = ll[i]; di > 0; di--) {
					pi = dp[ta[i] + di], qi = dq[ta[i] + di];
					dp[ta[i] + di] = INF, dq[ta[i] + di] = 0;
					for (dj = ll[j]; dj >= 0; dj--) {
						pj = dp[ta[j] + dj], qj = dq[ta[j] + dj];
						if (di + dj < k) {
							d = max(di, dj + 1);
							p_ = pi + pj;
							q = (long long) qi * qj % MD;
							if (dp[ta[i] + d] > p_)
								dp[ta[i] + d] = p_, dq[ta[i] + d] = 0;
							if (dp[ta[i] + d] == p_)
								dq[ta[i] + d] = (dq[ta[i] + d] + q) % MD;
						}
					}
				}
			}
		}
	}
}

int main() {
	static int uu[N - 1], vv[N - 1];
	int h, i, j, d, q;
	long long w, p;

	scanf("%d%d", &n, &k);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		uu[h] = i, vv[h] = j;
		eo[i]++, eo[j]++;
	}
	for (i = 0; i < n; i++) {
		ej[i] = ptr, ptr += eo[i];
		eo[i] = 0;
	}
	for (h = 0; h < n - 1; h++) {
		i = uu[h], j = vv[h];
		ej[i][eo[i]++] = j, ej[j][eo[j]++] = i;
	}
	dfs1(-1, 0, 0);
	for (d = 1; d <= n; d++)
		kk[d] += kk[d - 1];
	dfs2(-1, 0, 0);
	dfs3(-1, 0);
	for (i = 1; i <= n; i++)
		xx[i] += xx[i - 1];
	dfs4(-1, 0);
	w = 0;
	for (i = 0; i < n; i++)
		w += ww[i];
	w /= k;
	dfs5(-1, 0);
	query(ta[0], ta[0] + ll[0], &p, &q);
	if (p == w)
		printf("YES\n%d\n", q);
	else
		printf("NO\n0\n");
	return 0;
}

Compilation message (stderr)

wells.c: In function 'main':
wells.c:181:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  181 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~
wells.c:183:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  183 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 30