Submission #848510

#	Time	Username	Problem	Language	Result	Execution time	Memory
848510		qthang2k11	Chase (CEOI17_chase)	C++17	40 / 100	394 ms	524288 KiB

chase

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

#ifndef LOCAL
#define fprintf(...) {}
#endif

using ll = long long;

const int N = 1e5 + 5;

template<class X, class Y>
inline void maxi(X &x, Y y) {
	if (x < y) x = y;
}

vector<int> adj[N], g[N];
int n, k, a[N];
ll s[N];

ll ans = 0, INF;

struct Node {
	ll val[101][2];
	
	Node() { 
		memset(val, -63, sizeof val); 
	}
	
	void maxi_(const Node &other) {
		for (int i = 0; i <= k; i++)
			for (int j = 0; j < 2; j++)
				maxi(val[i][j], other.val[i][j]);
	}
	
	void deal(const Node &other, const int &x, const int &y) { // update from y to x
		for (int i = 0; i <= k; i++) {
			for (int j = 0; j < 2; j++) {
				ll cur = other.val[i][j];
				// if (i < k) maxi(val[i + 1][1], cur + s[x] - a[y] + (j ? a[y] : 0));
				if (i < k) {
					if (j) maxi(val[i + 1][1], cur + s[x] - a[y]);
					else maxi(val[i + 1][1], cur + s[x] - a[y]);
					maxi(val[i + 1][1], cur + s[x] - a[y] - (j ? a[x] : 0));
				}
				// maxi(val[i][0], cur + (j ? a[y] : 0));
				maxi(val[i][0], cur/* + (j ? a[x] : 0)*/);
			}
		}
	}
	
	Node deal_(const int &x, const int &y) { // update from y to x
		Node ans;
		for (int i = 0; i <= k; i++) {
			for (int j = 0; j < 2; j++) {
				ll cur = val[i][j];
				// if (i < k) maxi(ans.val[i + 1][1], cur + s[x] - a[y] + (j ? a[y] : 0));
				if (i < k) {
					if (j) maxi(ans.val[i + 1][1], cur + s[x] - a[y]);
					else maxi(ans.val[i + 1][1], cur + s[x] - a[y]);
					maxi(ans.val[i + 1][1], cur + s[x] - a[y] - (j ? a[x] : 0));
				}
				// maxi(ans.val[i][0], cur + (j ? a[y] : 0));
				maxi(ans.val[i][0], cur/* + (j ? a[x] : 0)*/);
			}
		}
		return ans;
	}
	
	ll res() const {
		ll ans = 0;
		for (int i = 0; i <= k; i++)
			for (int j = 0; j < 2; j++)
				maxi(ans, val[i][j]);
		return ans;
	}

};

vector<Node> pref[N], suf[N];
Node dp[N];

void dfs_init(int x, int p) {
	for (int y: adj[x]) {
		if (y == p) continue;
		g[x].emplace_back(y);
		dfs_init(y, x);
	}
}

void dfs(int x) {
	pref[x].resize(g[x].size());
	suf[x].resize(g[x].size());
	for (int y: g[x]) dfs(y);
	for (int i = 0, o = g[x].size(); i < o; i++) {
		int y = g[x][i];
		auto &p = pref[x][i];
		if (i) p.maxi_(pref[x][i - 1]);
		p.deal(dp[y], x, y);
	}
	for (int o = g[x].size(), i = o - 1; i >= 0; i--) {
		int y = g[x][i];
		auto &p = suf[x][i];
		if (i < o - 1) p.maxi_(suf[x][i + 1]);
		p.deal(dp[y], x, y);
	}
	if (!g[x].empty()) dp[x] = pref[x].back();
	// else {
		maxi(dp[x].val[0][0], 0);
		if (k > 0) maxi(dp[x].val[1][1], s[x]);
	// }
	maxi(ans, dp[x].res());
}

void dfs_reroot(int x, Node down) {
	maxi(down.val[0][0], 0);
	if (k > 0) maxi(down.val[1][1], s[x]);
	maxi(ans, down.res());
	for (int i = 0, o = g[x].size(); i < o; i++) {
		int y = g[x][i];
		Node cur = down;
		if (i > 0) cur.maxi_(pref[x][i - 1]);
		if (i + 1 < o) cur.maxi_(suf[x][i + 1]);
		dfs_reroot(y, cur.deal_(y, x));
	}
}

int32_t main() {
	cin.tie(0)->sync_with_stdio(0);
	cin >> n >> k;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
	for (int i = 1; i < n; i++) {
		int x, y;
		cin >> x >> y;
		adj[x].emplace_back(y);
		adj[y].emplace_back(x);
	}
	for (int x = 1; x <= n; x++) {
		for (int y: adj[x])
			s[x] += a[y];
	}
	dfs_init(1, 0);
	dfs(1);
	dfs_reroot(1, Node());
	cout << ans;
	return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 0 / 30
• Subtask 4: 0 / 30