Submission #753281

#	Time	Username	Problem	Language	Result	Execution time	Memory
753281		LeonaRaging	Election Campaign (JOI15_election_campaign)	C++14	10 / 100	121 ms	36276 KiB

election_campaign

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

#define pb push_back
#define db(val) "[" #val " = " << (val) << "] "

const int maxn = 1e5 + 4;
const int N = 16;

struct Query {
	int u, v, w;
	Query(int u = 0, int v = 0, int w = 0): u(u), v(v), w(w) {}
} q[maxn];

int n, m, h[maxn], tin[maxn], tout[maxn], up[maxn][20], dp[maxn], sum[maxn];
vector<int> adj[maxn], cross[maxn], down[maxn];

void dfs1(int u, int p) {
	tin[u] = ++tin[0];
	for (int j = 1; j <= N; j++)
		up[u][j] = up[up[u][j - 1]][j - 1];
	for (int v : adj[u])
		if (v != p) {
			h[v] = h[u] + 1;
			up[v][0] = u;
			dfs1(v, u);
		}
	tout[u] = tin[0];
}

bool isPar(int u, int p) {
	return tin[p] <= tin[u] && tout[p] >= tout[u];
}

int jump(int u, int v) {
	for (int j = N; j >= 0; j--)
		if (up[u][j] && !isPar(v, up[u][j]))
			u = up[u][j];
	return u;
}

void dfs2(int u, int p) {
	for (int v : adj[u]) if (v != p) {
		dfs2(v, u);
		sum[u] += dp[v];
	}
	dp[u] = sum[u];
	for (int i : cross[u]) {
		int a = q[i].u, b = q[i].v, w = q[i].w;
		dp[u] = max(dp[u], sum[u] - dp[jump(a, u)] - dp[jump(b, u)] + sum[a] + sum[b] + w);
	}
	for (int i : down[u]) {
		int v = q[i].v, w = q[i].w;
		dp[u] = max(dp[u], sum[u] - dp[jump(v, u)] + sum[v] + w);
	}
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin >> n;
    for (int i = 1, u, v; i < n; i++) {
    	cin >> u >> v;
    	adj[u].pb(v);
    	adj[v].pb(u);
    }
    dfs1(1, 0);
    cin >> m;
    for (int i = 1, u, v, w; i <= m; i++) {
    	cin >> u >> v >> w;
    	if (h[u] > h[v]) swap(u, v);
    	if (isPar(v, u)) 
    		down[u].pb(i);
    	else 
    		cross[up[jump(u, v)][0]].pb(i);
    	q[i] = Query(u, v, w);
    }
    dfs2(1, 0);
    cout << dp[1];
}

• Subtask 1: 0 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 0 / 30
• Subtask 5: 0 / 10
• Subtask 6: 0 / 40