Submission #545908

#	Time	Username	Problem	Language	Result	Execution time	Memory
545908		rainboy	Chase (CEOI17_chase)	C11	100 / 100	302 ms	172396 KiB

chase

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

#define N	100000
#define K	100

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

int *ej[N], eo[N];

void append(int i, int j) {
	int o = eo[i]++;

	if (o >= 2 && (o & o - 1) == 0)
		ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
	ej[i][o] = j;
}

int aa[N], k_; long long bb[N], dp[N][K + 1], dq[N][K + 1];

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

	memset(dp[i] + 1, -1, k_ * sizeof *dp[i]), dp[i][1] = bb[i];
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs1(i, j);
			for (k = 1; k <= k_; k++)
				dp[i][k] = max(dp[i][k], max(dp[j][k], dp[j][k - 1] == -1 ? -1 : dp[j][k - 1] + bb[i] - (k == 1 ? 0 : aa[j])));
		}
	}
}

void dfs2(int p, int i) {
	static long long max1[K + 1], max2[K + 1];
	static int jj[K + 1];
	int o, k;

	if (p == -1)
		memset(dq[i] + 1, -1, k_ * sizeof *dq[i]), dq[i][1] = bb[i];
	else
		for (k = k_; k >= 1; k--)
			if (dq[i][k - 1] != -1)
				dq[i][k] = max(dq[i][k], dq[i][k - 1] + bb[i] - (k == 1 ? 0 : aa[p]));
	memset(max1 + 1, -1, k_ * sizeof *max1);
	memset(max2 + 1, -1, k_ * sizeof *max2);
	memset(jj + 1, -1, k_ * sizeof *jj);
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			for (k = 1; k <= k_; k++) {
				long long x = max(dp[j][k], dp[j][k - 1] == -1 ? -1 : dp[j][k - 1] + bb[i] - (k == 1 ? 0 : aa[j]));

				if (max1[k] < x)
					max2[k] = max1[k], max1[k] = x, jj[k] = j;
				else if (max2[k] < x)
					max2[k] = x;
			}
	}
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			for (k = 1; k <= k_; k++)
				dq[j][k] = max(dq[i][k], jj[k] == j ? max2[k] : max1[k]);
	}
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p)
			dfs2(i, j);
	}
}

int main() {
	int n, h, i, j, k;
	long long ans;

	scanf("%d%d", &n, &k_);
	if (k_ == 0) {
		printf("0\n");
		return 0;
	}
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (i = 0; i < n; i++)
		scanf("%d", &aa[i]);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		bb[i] += aa[j], bb[j] += aa[i];
		append(i, j), append(j, i);
	}
	dfs1(-1, 0);
	dfs2(-1, 0);
	ans = 0;
	for (i = 0; i < n; i++)
		for (k = 0; k <= k_; k++)
			ans = max(ans, max(dp[i][k], dq[i][k]));
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

chase.c: In function 'append':
chase.c:15:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   15 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
chase.c: In function 'main':
chase.c:83:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |  scanf("%d%d", &n, &k_);
      |  ^~~~~~~~~~~~~~~~~~~~~~
chase.c:91:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~
chase.c:93:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

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