Submission #44608

#	Time	Username	Problem	Language	Result	Execution time	Memory
44608		ulna	Paprike (COI18_paprike)	C++11	0 / 100	114 ms	35328 KiB

paprike

#include <bits/stdc++.h>
using namespace std;

// why am I so weak

int n, k;
int a[100055];
int cut[100055];
long long dp[100055];

int pt[100055];
vector<int> g[100055];

typedef pair<long long, int> P;

#define ft first
#define sd second

void dfs(int v, int par = -1) {
	dp[v] = a[v];

	for (auto u : g[v]) if (u != par) {
		dfs(u, v);
		dp[v] += dp[u];
		cut[v] += cut[u];
	}

	sort(g[v].begin(), g[v].end(), [&] (int u, int v) {
		return dp[u] > dp[v];
	});

	pt[v] = n;

	for (int i = 0; i < (int)g[v].size(); i++) {
		int u = g[v][i];

		if (u == par) continue;

		if (dp[v] <= k) {
			pt[v] = i;
			break;
		}

		cut[v]++;
		dp[v] -= dp[u];
	}
}

int res = INT_MAX;

void rdfs(int v, int par = -1, P ac = P(0, 0)) {
	int temp = 0;
	dp[v] += ac.ft;
	bool diu = false;

	while (dp[v] > k) {
		if (pt[v] >= (int)g[v].size()) {
			dp[v] -= ac.ft;
			temp++;
			continue;
		}
		int u = g[v][pt[v]];

		if (!diu && ac.ft >= dp[u]) {
			diu = true;
			dp[v] -= ac.ft;
			temp++;
			continue;
		}

		pt[v]++;

		if (u == par) continue;

		temp++;
		dp[v] -= dp[u];
	}

	res = min(res, ac.sd + temp + cut[v]);

	for (int i = 0; i < (int)g[v].size(); i++) {
		int u = g[v][i];

		if (u == par) continue;

		if (i < pt[i]) {
			rdfs(u, v, P(dp[v], ac.sd + temp + cut[v] - 1));
		} else {
			int cur = dp[v] - dp[u];
			int spe = 0;

			for (int j = pt[v] - 1; j >= 0; j--) {
				int u = g[v][j];

				if (u == par) continue;

				if (cur + dp[u] > k) break;

				cur += dp[u];
				spe++;
			}

			rdfs(u, v, P(cur, ac.sd + temp + cut[v] - spe));
		}
	}
}
int main() {
	cin >> n >> k;

	for (int i = 0; i < n; i++) scanf("%d", &a[i]);

	for (int i = 0; i + 1 < n; i++) {
		int x, y;
		scanf("%d %d", &x, &y);
		x--, y--;

		g[x].push_back(y);
		g[y].push_back(x);
	}

	dfs(0);
	rdfs(0);
	
	printf("%d\n", res);

	return 0;
}

Compilation message (stderr)

paprike.cpp: In function 'int main()':
paprike.cpp:110:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
                              ~~~~~^~~~~~~~~~~~~
paprike.cpp:114:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &x, &y);
   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 13
• Subtask 3: 0 / 27
• Subtask 4: 0 / 49