Submission #948959

#	Time	Username	Problem	Language	Result	Execution time	Memory
948959		rainboy	Triumphal arch (POI13_luk)	C11	100 / 100	657 ms	25628 KiB

luk

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

#define N	300000

int max(int a, int 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 dp[N], k;

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

	dp[i] = 0;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs(i, j);
			dp[i] += dp[j];
		}
	}
	dp[i] = max(dp[i] - k, 0) + 1;
}

int main() {
	int n, h, i, j, lower, upper;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		append(i, j), append(j, i);
	}
	lower = -1, upper = n;
	while (upper - lower > 1) {
		k = (lower + upper) / 2;
		dfs(-1, 0);
		if (dp[0] == 1)
			upper = k;
		else
			lower = k;
	}
	printf("%d\n", upper);
	return 0;
}

Compilation message (stderr)

luk.c: In function 'append':
luk.c:13:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   13 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
luk.c: In function 'main':
luk.c:38:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
luk.c:42:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10