Submission #557027

#	Time	Username	Problem	Language	Result	Execution time	Memory
557027		rainboy	Election Campaign (JOI15_election_campaign)	C11	100 / 100	149 ms	25848 KiB

election_campaign

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

#define N	100000
#define M	100000

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

void append(int **ej, int *eo, 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 uu[M], vv[M], ww[M];
int *ej[N], eo[N], *eh[N], eo_[N], dd[N], pp[N], qq[N], ta[N], tb[N], n; long long dp[N];

int dfs1(int p, int i, int d) {
	int o, s, k_, j_;

	dd[i] = d, pp[i] = p;
	s = 1, k_ = 0, j_ = -1;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			int k = dfs1(i, j, d + 1);

			s += k;
			if (k_ < k)
				k_ = k, j_ = j;
		}
	}
	qq[i] = j_;
	return s;
}

void dfs2(int p, int i, int q) {
	static int time;
	int o, j_;

	ta[i] = time++;
	j_ = qq[i], qq[i] = q;
	if (j_ != -1)
		dfs2(i, j_, q);
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p && j != j_)
			dfs2(i, j, j);
	}
	tb[i] = time;
}

int lca(int i, int j) {
	while (qq[i] != qq[j])
		if (dd[qq[i]] > dd[qq[j]])
			i = pp[qq[i]];
		else
			j = pp[qq[j]];
	return dd[i] < dd[j] ? i : j;
}

long long ft[N];

void update(int i, int n, long long x) {
	while (i < n) {
		ft[i] += x;
		i |= i + 1;
	}
}

long long query(int i) {
	long long x = 0;

	while (i >= 0) {
		x += ft[i];
		i &= i + 1, i--;
	}
	return x;
}

void dfs3(int p, int i) {
	int o;
	long long x, y;

	x = 0;
	for (o = eo[i]; o--; ) {
		int j = ej[i][o];

		if (j != p) {
			dfs3(i, j);
			x += dp[j];
		}
	}
	y = 0;
	for (o = eo_[i]; o--; ) {
		int h = eh[i][o];

		y = max(y, ww[h] - (uu[h] == i ? 0 : query(ta[uu[h]])) - (vv[h] == i ? 0 : query(ta[vv[h]])));
	}
	dp[i] = x + y;
	update(ta[i], n, y), update(tb[i], n, -y);
}

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

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		ej[i] = (int *) malloc(2 * sizeof *ej[i]);
		eh[i] = (int *) malloc(2 * sizeof *eh[i]);
	}
	for (h = 0; h < n - 1; h++) {
		scanf("%d%d", &i, &j), i--, j--;
		append(ej, eo, i, j), append(ej, eo, j, i);
	}
	dfs1(-1, 0, 0);
	dfs2(-1, 0, 0);
	scanf("%d", &m);
	for (h = 0; h < m; h++) {
		scanf("%d%d%d", &uu[h], &vv[h], &ww[h]), uu[h]--, vv[h]--;
		append(eh, eo_, lca(uu[h], vv[h]), h);
	}
	dfs3(-1, 0);
	printf("%lld\n", dp[0]);
	return 0;
}

Compilation message (stderr)

election_campaign.c: In function 'append':
election_campaign.c:12:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   12 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
election_campaign.c: In function 'main':
election_campaign.c:111:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
election_campaign.c:117:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  117 |   scanf("%d%d", &i, &j), i--, j--;
      |   ^~~~~~~~~~~~~~~~~~~~~
election_campaign.c:122:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  122 |  scanf("%d", &m);
      |  ^~~~~~~~~~~~~~~
election_campaign.c:124:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
  124 |   scanf("%d%d%d", &uu[h], &vv[h], &ww[h]), uu[h]--, vv[h]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 30 / 30
• Subtask 5: 10 / 10
• Subtask 6: 40 / 40