Submission #388028

#	Time	Username	Problem	Language	Result	Execution time	Memory
388028		rainboy	Dreaming (IOI13_dreaming)	C11	47 / 100	95 ms	20972 KiB

dreaming

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

#define N	100000
#define INF	0x3f3f3f3f

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

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

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

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

char rr[N]; int dp[N], ans;

void dfs1(int p, int i, int r) {
	int o, d1, d2;

	if (rr[i] != -1)
		return;
	rr[i] = r, d1 = 0, d2 = 0;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o], w = ew[i][o];

		if (j != p) {
			dfs1(i, j, r);
			if (d1 < dp[j] + w)
				d2 = d1, d1 = dp[j] + w;
			else if (d2 < dp[j] + w)
				d2 = dp[j] + w;
		}
	}
	ans = max(ans, d1 + d2);
	dp[i] = d1;
}

int r;

void dfs2(int p, int i, int d) {
	int o, d1, d2, j1;

	r = min(r, max(dp[i], d));
	d1 = 0, d2 = 0, j1 = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o], w = ew[i][o];

		if (j != p) {
			if (d1 < dp[j] + w)
				d2 = d1, d1 = dp[j] + w, j1 = j;
			else if (d2 < dp[j] + w)
				d2 = dp[j] + w;
		}
	}
	for (o = eo[i]; o--; ) {
		int j = ej[i][o], w = ew[i][o];

		if (j != p)
			dfs2(i, j, max(d, j == j1 ? d2 : d1) + w);
	}
}

int travelTime(int n, int m, int l, int ii[], int jj[], int ww[]) {
	int h, i, r1, r2;

	for (i = 0; i < n; i++) {
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
		ew[i] = (int *) malloc(2 * sizeof *ew[i]);
	}
	for (h = 0; h < m; h++)
		append(ii[h], jj[h], ww[h]), append(jj[h], ii[h], ww[h]);
	if (m < n - 2)
		return -1;
	memset(rr, -1, n * sizeof *rr);
	ans = 0;
	r = INF, dfs1(-1, 0, 0), dfs2(-1, 0, 0), r1 = r;
	if (m == n - 1)
		return ans;
	r2 = 0;
	for (i = 0; i < n; i++)
		if (rr[i] == -1) {
			r = INF, dfs1(-1, i, i), dfs2(-1, i, 0), r2 = r;
			break;
		}
	ans = max(ans, r1 + l + r2);
	return ans;
}

Compilation message (stderr)

dreaming.c: In function 'append':
dreaming.c:17:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   17 |  if (o >= 2 && (o & o - 1) == 0) {
      |                     ~~^~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23