Submission #391443

#	Time	Username	Problem	Language	Result	Execution time	Memory
391443		osaaateiasavtnl	Beads and wires (APIO14_beads)	C++14	100 / 100	227 ms	34184 KiB

beads

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <queue>
#include <ctime>
#include <cassert>
#include <complex>
#include <string>
#include <cstring>
#include <chrono>
#include <random>
#include <bitset>
#include <fstream>
using namespace std;
#define int long long
#define ii pair <int, int>
#define app push_back
#define all(a) a.begin(), a.end()
#define bp __builtin_popcountll
#define ll long long
#define mp make_pair
#define x first
#define y second
#define Time (double)clock()/CLOCKS_PER_SEC
#define debug(x) std::cerr << #x << ": " << x << '\n';
#define FOR(i, n) for (int i = 0; i < n; ++i)
#define FORN(i, n) for (int i = 1; i <= n; ++i)
#define pb push_back
#define trav(a, x) for (auto& a : x)
using vi = vector<int>;
template <typename T>
std::istream& operator >>(std::istream& input, std::vector<T>& data)
{
    for (T& x : data)
        input >> x;
    return input;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const pair <T, T> & data)
{
    output << "(" << data.x << "," << data.y << ")";
    return output;
}
template <typename T>
std::ostream& operator <<(std::ostream& output, const std::vector<T>& data)
{
    for (const T& x : data)
        output << x << " ";
    return output;
}
ll div_up(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll div_down(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down 
ll math_mod(ll a, ll b) { return a - b * div_down(a, b); }
#define tcT template<class T
#define tcTU tcT, class U
tcT> using V = vector<T>; 
tcT> void re(V<T>& x) { 
    trav(a, x)
        cin >> a;
}
tcT> bool ckmin(T& a, const T& b) {
    return b < a ? a = b, 1 : 0; 
} // set a = min(a,b)
tcT> bool ckmax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0; 
}
ll gcd(ll a, ll b) {
    while (b) {
        tie(a, b) = mp(b, a % b);
    }
    return a;
}
 
const int N = 2e5+7, INF = 1e18;
 
int n;
V <ii> g[N];
int dp[N][2][2]; // hor, up
void dfs(int u, int p, int UP) {
	int sum = 0, mx = 0;
	vi a, b, c;
	trav (e, g[u]) {
		int v = e.x;
		if (v != p) {
			dfs(v, u, e.y);
			sum += dp[v][0][1];
			a.app(e.y + dp[v][1][0] - dp[v][0][1]);
			b.app(e.y + dp[v][0][0] - dp[v][0][1]);
			c.app(dp[v][1][1] - dp[v][0][1]);
			ckmax(mx, dp[v][1][1] - dp[v][0][1]);
		}
	}
	dp[u][0][0] = sum;
	int sz = a.size();
	if (sz >= 2) {
		vi pref(sz + 1, -INF), suf(sz + 1, -INF);
		FOR (i, sz) {
			pref[i + 1] = max(pref[i], a[i]);
		}
		for (int i = sz - 1; i >= 0; --i) {
			suf[i] = max(suf[i + 1], a[i]);
		}
		FOR (i, sz) {
			ckmax(dp[u][1][0], sum + b[i] + max(pref[i], suf[i + 1]));
		}
	}
	if (sz) {
		trav (e, a) {
			ckmax(dp[u][1][1], sum + e + UP);	
		}
		trav (e, b) {
			ckmax(dp[u][0][1], sum + e + UP);	
		}
		ckmax(dp[u][1][0], sum + mx);
	}
	FOR (x, 2) {
		FOR (y, 2) {
			if (!x) {
				ckmax(dp[u][x + 1][y], dp[u][x][y]);
			}
			if (!y) {
				ckmax(dp[u][x][y + 1], dp[u][x][y]);
			}
		}
	}
}
 
signed main() {
    #ifdef LOCAL
    #else
    #define endl '\n'
    ios_base::sync_with_stdio(0); cin.tie(0);
    #endif
    cin >> n;
    FOR (i, n - 1) {
    	int u, v, c;
    	cin >> u >> v >> c;
    	g[u].app(mp(v, c));
    	g[v].app(mp(u, c));
    }
    dfs(1, 1, 0);
    cout << dp[1][1][0] << endl;
}

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