Submission #875944

#	Time	Username	Problem	Language	Result	Execution time	Memory
875944		rainboy	Tax Evasion (LMIO19_mokesciai)	C11	100 / 100	57 ms	36524 KiB

mokesciai

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

#define N	200000

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;
}

int qu[N], pp[N], dd[N], rr[N];

void dfs1(int p, int i, int d) {
	int o;

	qu[d] = i;
	pp[i] = p, dd[i] = d, rr[i] = d == 0 ? -1 : qu[d / 2 + 1];
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		dfs1(i, j, d + 1);
	}
}

int cc[N], kk[N], jj[N], qq[N], d_;

void dfs2(int i) {
	int o, j_, u, v;

	kk[i] = 1;
	j_ = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		dfs2(j);
		if (qq[j] != -1) {
			if (j_ == -1)
				j_ = j;
			else if (dd[qq[j_]] < dd[qq[j]]) {
				for (u = j_, v = j; u != qq[j_]; u = jj[u], v = jj[v])
					kk[v] += kk[u];
				kk[v] += kk[u];
				j_ = j;
			} else {
				for (u = j_, v = j; v != qq[j]; u = jj[u], v = jj[v])
					kk[u] += kk[v];
				kk[u] += kk[v];
			}
		}
	}
	jj[i] = j_, qq[i] = j_ == -1 ? i : qq[j_];
	while (cc[i]--) {
		d_ = min(d_, dd[qq[i]]);
		if (--kk[qq[i]] == 0)
			qq[i] = qq[i] == i ? -1 : pp[qq[i]];
	}
}

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

	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++)
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
	for (j = 1; j < n; j++) {
		scanf("%d", &i), i--;
		append(i, j);
	}
	dfs1(-1, 0, 0);
	while (m--) {
		scanf("%d", &i), i--;
		if (i == 0) {
			printf("1\n");
			return 0;
		}
		cc[rr[i]]++;
	}
	d_ = n;
	dfs2(0);
	printf("%d\n", d_ + 1);
	return 0;
}

Compilation message (stderr)

mokesciai.c: In function 'append':
mokesciai.c:13:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   13 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
mokesciai.c: In function 'main':
mokesciai.c:69:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
mokesciai.c:73:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |   scanf("%d", &i), i--;
      |   ^~~~~~~~~~~~~~~
mokesciai.c:78:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   78 |   scanf("%d", &i), i--;
      |   ^~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 22 / 22
• Subtask 3: 39 / 39
• Subtask 4: 29 / 29