Submission #740625

#	Time	Username	Problem	Language	Result	Execution time	Memory
740625		rainboy	Mountains and Valleys (CCO20_day1problem3)	C11	0 / 25	2 ms	672 KiB

Main

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

#define N	500000
#define M	2000000

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 d_, i_;

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

	if (d_ < d)
		d_ = d, i_ = i;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];
		
		if (j != p)
			dfs(i, j, d + 1);
	}
}

int ii[M], jj[M], ww[M];

int main() {
	int n, m, h, i, j, u, v, w;

	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d%d", &i, &j, &w);
		ii[h] = i, jj[h] = j, ww[h] = w;
		if (w == 1)
			append(i, j), append(j, i);
	}
	d_ = i_ = -1, dfs(-1, 0, 0);
	u = i_, d_ = i_ = -1, dfs(-1, u, 0);
	v = i_;
	printf("%d\n", (n - 1) * 2 - d_);
	return 0;
}

Compilation message (stderr)

Main.c: In function 'append':
Main.c:12:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   12 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
Main.c: In function 'main':
Main.c:35:24: warning: variable 'v' set but not used [-Wunused-but-set-variable]
   35 |  int n, m, h, i, j, u, v, w;
      |                        ^
Main.c:37:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
Main.c:41:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |   scanf("%d%d%d", &i, &j, &w);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 1
• Subtask 2: 0 / 2
• Subtask 3: 0 / 2
• Subtask 4: 0 / 6
• Subtask 5: 0 / 2
• Subtask 6: 0 / 3
• Subtask 7: 0 / 5
• Subtask 8: 0 / 4