Submission #32025

#	Time	Username	Problem	Language	Result	Execution time	Memory
32025		minimario	Beads and wires (APIO14_beads)	C++14	0 / 100	4 ms	2688 KiB

beads

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

#define f first
#define s second
const int MAX = 100005;
typedef pair<int, int> pii;

vector<pii> g[MAX];
int dp[MAX][2];
void dfs(int u, int p=-1, int len=-1) {
	for (pii i : g[u]) {
		if (i.f == p) { continue; }
		dfs(i.f, u, i.s);
	}
	int sum = 0;
	vector<int> subtract;
	for (pii i : g[u]) {
		if (i.f == p) { continue; }
		sum += max(dp[i.f][0], dp[i.f][1]);
		subtract.push_back(max(dp[i.f][0], dp[i.f][1]) - i.s - dp[i.f][0]);
	}
	sort(subtract.begin(), subtract.end());
	if (subtract.size() >= 2) {
		dp[u][0] = sum - subtract[0] - subtract[1];
	}
	if (p != -1) {
		for (pii i : g[u]) {
			if (i.f == p) { continue; }
			dp[u][1] = max(dp[u][1], sum + len + i.s - max(dp[i.f][0], dp[i.f][1]) + dp[i.f][0]);
		}
	}
	dp[u][0] = max(dp[u][0], sum);
	// cout << u << " " << dp[u][0] << " " << dp[u][1] << endl;

}
int main() {
	//freopen("a.in", "r", stdin);
	//freopen("a.out", "w", stdout);
	int n; scanf("%d", &n);
	for (int i=0; i<n-1; i++) {
		int u, v, w; scanf("%d %d %d", &u, &v, &w);
		g[u].push_back({v, w});
		g[v].push_back({u, w});
	}
	dfs(1);
	printf("%d\n", max(dp[1][0], dp[1][1]));
}

Compilation message (stderr)

beads.cpp: In function 'int main()':
beads.cpp:40:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int n; scanf("%d", &n);
         ~~~~~^~~~~~~~~~
beads.cpp:42:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int u, v, w; scanf("%d %d %d", &u, &v, &w);
                ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43