Submission #501227

#	Time	Username	Problem	Language	Result	Execution time	Memory
501227		rainboy	Wells (CEOI21_wells)	C11	0 / 100	1 ms	332 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 du[N * 2]; int dv[N * 2];

void update(int l, int r, long long u, int v) {
	int i;

	for (i = l; i <= r; i++) {
		du[i] += u, dv[i] = (long long) dv[i] * v % MD;
		if (du[i] > INF)
			du[i] = INF, dv[i] = 0;
	}
}

void query(int l, int r, long long *u_, int *v_) {
	int i;
	long long u;
	int v;

	u = INF, v = 0;
	for (i = l; i <= r; i++) {
		if (u > du[i])
			u = du[i], v = 0;
		if (u == du[i])
			v = (v + dv[i]) % MD;
	}
	*u_ = u, *v_ = v;
}

void process(int i, int j, int d) {
	long long u1, ui, uj, u;
	int v1, vi, vj, v;

	u1 = INF, v1 = 0;
	ui = du[ta[i] + d], vi = dv[ta[i] + d];
	query(ta[j], ta[j] + min(ll[j], min(k - d - 1, d - 2)), &uj, &vj);
	u = ui + uj;
	v = (long long) vi * vj % MD;
	if (u1 > u)
		u1 = u, v1 = 0;
	if (u1 == u)
		v1 = (v1 + v) % MD;
	if (d - 1 <= ll[j]) {
		uj = du[ta[j] + d - 1], vj = dv[ta[j] + d - 1];
		query(ta[i] + 1, ta[i] + min(k - d, d), &ui, &vi);
		u = ui + uj;
		v = (long long) vi * vj % MD;
		if (u1 > u)
			u1 = u, v1 = 0;
		if (u1 == u)
			v1 = (v1 + v) % MD;
	}
	du[ta[i] + d] = u1, dv[ta[i] + d] = v1;
}

void dfs5(int p, int i) {
	int o, j, d;
	long long u;
	int v;

	du[ta[i] + 0] = ww[i], dv[ta[i] + 0] = 1;
	if (jj[i] == -1)
		du[ta[i] + 1] = 0, dv[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], &u, &v);
		du[ta[i] + 0] += u, dv[ta[i] + 0] = v;
		if (ll[i] >= k)
			du[ta[i] + k] = INF, dv[ta[i] + k] = 0;
		for (o = eo[i]; o--; ) {
			j = ej[i][o];
			if (j != p && j != jj[i]) {
				int lower, upper;

				query(ta[j], ta[j] + ll[j], &u, &v);
				du[ta[i] + 0] += u, dv[ta[i] + 0] = (long long) dv[ta[i] + 0] * v % MD;
				lower = ll[j] + 2, upper = k - 1 - ll[j];
				if (lower > upper)
					for (d = min(ll[i], k); d > 0; d--)
						process(i, j, d);
				else {
					for (d = min(ll[i], k); d > upper; d--)
						process(i, j, d);
					query(ta[j], ta[j] + ll[j], &u, &v);
					update(ta[i] + lower, ta[i] + upper, u, v);
					for (d = lower - 1; d >= 0; d--)
						process(i, j, d);
				}
			}
		}
	}
}

int main() {
	static int ii_[N - 1], jj_[N - 1];
	int h, i, j, d, v;
	long long w, u;

	scanf("%d%d", &n, &k);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		ii_[h] = i, jj_[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 = ii_[h], j = jj_[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], &u, &v);
	if (u == w)
		printf("YES\n%d\n", v);
	else
		printf("NO\n0\n");
	return 0;
}

Compilation message (stderr)

wells.c: In function 'main':
wells.c:208:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  208 |  scanf("%d%d", &n, &k);
      |  ^~~~~~~~~~~~~~~~~~~~~
wells.c:210:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  210 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

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