Submission #31627

#	Time	Username	Problem	Language	Result	Execution time	Memory
31627		aome	Beads and wires (APIO14_beads)	C++14	28 / 100	1075 ms	8704 KiB

beads

/*input
5
1 2 10
1 3 40
1 4 15
1 5 20
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <utility>
#include <vector>
using namespace std;
#define sp ' '
#define endl '\n'
#define fi first
#define se second
#define mp make_pair
#define int long long
#define N 200005

int n;
vector<vector<pair<int, int> > > a(N);
int dp[N][2];

int cal(int u, int p, bool up, int price) {
	int &ret = dp[u][up];
	if (ret != -1) return ret;
	ret = 0;
	int sum = 0;
	for (int i = 0; i < a[u].size(); i++) {
		int v = a[u][i].fi; if (v == p) continue;
		sum += cal(v, u, 0, a[u][i].se);
	}
	ret = max(ret, sum);
	if (!up) {
		for (int i = 0; i < a[u].size(); i++) {
			int v = a[u][i].fi; if (v == p) continue;
			ret = max(ret, sum - cal(v, u, 0, a[u][i].se) + cal(v, u, 1, a[u][i].se) + a[u][i].se + price);
		}
	}
	return ret;
}

int ans = 0;
void modify(int u, int p, int price) {
	if (u != 1) {
		dp[p][0] = dp[p][1] = -1;
		dp[u][0] = dp[u][1] = -1;
		ans = max(ans, cal(u, u, 1, 0));
	}
	else {
		ans = max(ans, cal(u, u, 1, 0));
	}
	for (int i = 0; i < a[u].size(); i++) {
		int v = a[u][i].fi; if (v == p) continue;
		int x0 = dp[v][0], x1 = dp[v][1], y0 = dp[u][0], y1 = dp[u][1];
		modify(v, u, a[u][i].se);
		dp[v][0] = x0; dp[v][1] = x1; dp[u][0] = y0; dp[u][1] = y1;
	}
}

signed main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
#ifdef UncleGrandpa
	freopen("1test.inp", "r", stdin);
#endif
	cin >> n;
	for (int i = 1; i <= n - 1; i++) {
		int u, v, c; cin >> u >> v >> c;
		a[u].push_back(mp(v, c));
		a[v].push_back(mp(u, c));
	}
	memset(dp, -1, sizeof(dp));
	modify(1, 1, 0);
	cout << ans << endl;
}

Compilation message (stderr)

beads.cpp: In function 'long long int cal(long long int, long long int, bool, long long int)':
beads.cpp:57:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a[u].size(); i++) {
                  ~~^~~~~~~~~~~~~
beads.cpp:63:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < a[u].size(); i++) {
                   ~~^~~~~~~~~~~~~
beads.cpp: In function 'void modify(long long int, long long int, long long int)':
beads.cpp:81:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < a[u].size(); i++) {
                  ~~^~~~~~~~~~~~~

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