Submission #545911

#	Time	Username	Problem	Language	Result	Execution time	Memory
545911		rainboy	One-Way Streets (CEOI17_oneway)	C11	100 / 100	103 ms	13728 KiB

oneway

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

#define N	100000
#define M	100000

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

int ii[M], jj[M]; char cc[M + 1];
int *eh[N], eo[N];

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

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

int ta[N], tb[N], kk[N];

void dfs(int f, int i) {
	static int time;
	int o;

	ta[i] = tb[i] = ++time;
	for (o = eo[i]; o--; ) {
		int h = eh[i][o], j = i ^ ii[h] ^ jj[h];

		if (h != f) {
			if (!ta[j]) {
				dfs(h, j);
				if (tb[j] != ta[j] || kk[j] == 0)
					cc[h] = 'B';
				else
					cc[h] = (i == ii[h]) == (kk[j] < 0) ? 'R' : 'L';
				tb[i] = min(tb[i], tb[j]);
				kk[i] += kk[j];
			} else {
				cc[h] = 'B';
				tb[i] = min(tb[i], ta[j]);
			}
		}
	}
}

int main() {
	int n, m, q, h, i, j;

	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++)
		eh[i] = (int *) malloc(2 * sizeof *eh[i]);
	for (h = 0; h < m; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		ii[h] = i, jj[h] = j;
		append(i, h), append(j, h);
	}
	scanf("%d", &q);
	while (q--) {
		scanf("%d%d", &i, &j), i--, j--;
		kk[i]++, kk[j]--;
	}
	for (i = 0; i < n; i++)
		if (!ta[i])
			dfs(-1, i);
	printf("%s\n", cc);
	return 0;
}

Compilation message (stderr)

oneway.c: In function 'append':
oneway.c:15:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   15 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
oneway.c: In function 'main':
oneway.c:50:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
oneway.c:54:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~
oneway.c:58:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |  scanf("%d", &q);
      |  ^~~~~~~~~~~~~~~
oneway.c:60:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40