Submission #545928

#	Time	Username	Problem	Language	Result	Execution time	Memory
545928		rainboy	Dynamic Diameter (CEOI19_diameter)	C11	100 / 100	427 ms	50824 KiB

diameter

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

#define N	100000
#define N_	(1 << 18)	/* N_ = pow2(ceil(log2((N - 1) * 2))) */

long long max(long long a, long long b) { return a > b ? a : b; }

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 ii[N - 1], jj[N - 1], ta[N - 1], tb[N - 1]; long long ww[N - 1], aa[(N - 1) * 2];

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

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

		if (j != p) {
			ii[h] = i, jj[h] = j;
			ta[h] = time++;
			dfs(i, j);
			tb[h] = time++;
			aa[ta[h]] = ww[h], aa[tb[h]] = -ww[h];
		}
	}
}

long long st1[N_ * 2], st2[N_ * 2], st01[N_ * 2], st12[N_ * 2], st23[N_ * 2], st02[N_ * 2], st13[N_ * 2], st03[N_ * 2]; int n_;

void pul(int i) {
	int l = i << 1 | 0, r = l | 1;

	st1[i] = st1[l] + st1[r];
	st2[i] = st2[l] + st2[r];
	st01[i] = max(st01[r], st01[l] + st1[r]);
	st12[i] = max(st1[l] + st12[r], st12[l] + st2[r]);
	st23[i] = max(st2[l] + st23[r], st23[l]);
	st02[i] = max(max(st02[r], st01[l] + st12[r]), st02[l] + st2[r]);
	st13[i] = max(max(st1[l] + st13[r], st12[l] + st23[r]), st13[l]);
	st03[i] = max(max(max(st03[r], st01[l] + st13[r]), st02[l] + st23[r]), st03[l]);
}

void build(long long *aa, int n) {
	int i;

	n_ = 1;
	while (n_ < n)
		n_ <<= 1;
	for (i = 0; i < n; i++) {
		st1[n_ + i] = -aa[i];
		st2[n_ + i] = aa[i];
		st01[n_ + i] = max(0, -aa[i]);
		st23[n_ + i] = max(aa[i], 0);
		st12[n_ + i] = st02[n_ + i] = st13[n_ + i] = st03[n_ + i] = max(-aa[i], aa[i]);
	}
	for (i = n_ - 1; i > 0; i--)
		pul(i);
}

void update(int i, long long w) {
	i += n_;
	st1[i] = -w;
	st2[i] = w;
	st01[i] = max(0, -w);
	st23[i] = max(w, 0);
	st12[i] = st02[i] = st13[i] = st03[i] = max(-w, w);
	while (i > 1)
		pul(i >>= 1);
}

int main() {
	int n, q, h, i;
	long long w_, last;

	scanf("%d%d%lld", &n, &q, &w_);
	for (i = 0; i < n; i++)
		eh[i] = (int *) malloc(2 * sizeof *eh[i]);
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d%lld", &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
		append(ii[h], h), append(jj[h], h);
	}
	dfs(-1, 0);
	build(aa, (n - 1) * 2);
	last = 0;
	while (q--) {
		int h;
		long long w;

		scanf("%d%lld", &h, &w), h = (h + last) % (n - 1), w = (w + last) % w_;
		ww[h] = w;
		update(ta[h], ww[h]), update(tb[h], -ww[h]);
		printf("%lld\n", last = st03[1]);
	}
	return 0;
}

Compilation message (stderr)

diameter.c: In function 'append':
diameter.c:14:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   14 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
diameter.c: In function 'main':
diameter.c:85:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   85 |  scanf("%d%d%lld", &n, &q, &w_);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.c:89:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |   scanf("%d%d%lld", &ii[h], &jj[h], &ww[h]), ii[h]--, jj[h]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.c:99:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |   scanf("%d%lld", &h, &w), h = (h + last) % (n - 1), w = (w + last) % w_;
      |   ^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 7 / 7
• Subtask 4: 18 / 18
• Subtask 5: 24 / 24
• Subtask 6: 27 / 27