Submission #482871

#	Time	Username	Problem	Language	Result	Execution time	Memory
482871		rainboy	Svjetlo (COCI20_svjetlo)	C11	110 / 110	592 ms	113360 KiB

svjetlo

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

#define N	500000
#define INF	0x3f3f3f3f

int min(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;
}

char cc[N + 1], empty[N];
int dp[N][3][3];

void dfs(int p, int i) {
	static int dq[3][3][2], dr[3][3][2];
	int o, k, e, c, k1, e1, c1, k2, e2, j_;

	empty[i] = cc[i] == '1';
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs(i, j);
			if (!empty[j])
				empty[i] = 0;
		}
	}
	for (k = 0; k <= 2; k++)
		for (e = 0; e <= 2; e++)
			for (c = 0; c < 2; c++)
				dq[k][e][c] = INF;
	c = cc[i] - '0';
	dq[0][0][c] = 0, dq[0][1][c ^ 1] = 2, dq[0][2][c] = 4;
	dq[1][0][c ^ 1] = 1, dq[1][1][c] = 3, dq[1][2][c ^ 1] = 5;
	dq[2][0][c ^ 1] = 1, dq[2][1][c] = 3, dq[2][2][c ^ 1] = 5;
	j_ = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			if (!empty[j]) {
				for (k = 0; k <= 2; k++)
					for (e = 0; e <= 2; e++)
						for (c = 0; c < 2; c++)
							dr[k][e][c] = INF;
				j_ = j_ == -1 ? j : -2;
			} else {
				for (k = 0; k <= 2; k++)
					for (e = 0; e <= 2; e++)
						for (c = 0; c < 2; c++)
							dr[k][e][c] = dq[k][e][c];
			}
			for (k1 = 0; k1 <= 2; k1++)
				for (e1 = 0; e1 <= 2; e1++)
					for (c1 = 0; c1 < 2; c1++)
						for (k2 = 0; k1 + k2 <= 2; k2++)
							for (e2 = 0; e2 <= 2; e2++) {
								int x = dq[k1][e1][c1] + dp[j][k2][e2];

								if (k2 != 1 && e2 == 0)
									continue;
								k = k1 + k2, e = e1, c = c1 ^ (e2 & 1);
								if (k1 == 0 && k2 == 1)
									x++, c ^= 1;
								dr[k][e][c] = min(dr[k][e][c], x);
							}
			for (k = 0; k <= 2; k++)
				for (e = 0; e <= 2; e++)
					for (c = 0; c < 2; c++)
						dq[k][e][c] = dr[k][e][c];
		}
	}
	c = cc[i] - '0';
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p && (j_ == -1 || j == j_))
			dq[0][0][c] = min(dq[0][0][c], dp[j][0][0]), dq[2][0][c] = min(dq[2][0][c], dp[j][2][0]);
	}
	c = 1;
	for (k = 0; k <= 2; k++)
		for (e = 0; e <= 2; e++)
			dp[i][k][e] = dq[k][e][c];
}

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

	scanf("%d%s", &n, cc);
	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);
	}
	dfs(-1, 0);
	printf("%d\n", dp[0][2][0]);
	return 0;
}

Compilation message (stderr)

svjetlo.c: In function 'append':
svjetlo.c:14:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   14 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
svjetlo.c: In function 'main':
svjetlo.c:97:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   97 |  scanf("%d%s", &n, cc);
      |  ^~~~~~~~~~~~~~~~~~~~~
svjetlo.c:101:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~

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