Submission #1210644

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210644		nguyn	Election Campaign (JOI15_election_campaign)	C++20	100 / 100	124 ms	46152 KiB

election_campaign

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

#define int long long
#define ll long long 
#define F first
#define S second
#define pb push_back 
#define pii pair<int,int>

const int N = 2e5 + 5;

struct BIT {
	vector<int> bit;
	int n;

	BIT() {}
	BIT(int _n) : n(_n) {
		bit.resize(n + 3); 
	}

	void update(int id, int val) {
		for (int i = id; i <= n; i += (i & -i)) bit[i] += val; 
	}

	int get(int id) {
		int res = 0;
		for (int i = id; i > 0; i -= (i & -i)) res += bit[i];
		return res; 
	}
} res, total; 

int n, m;

struct Data {
	int u, v, c;

	Data() {}
	Data(int _u, int _v, int _c) : u(_u), v(_v), c(_c) {}
};

vector<int> g[N]; 
vector<Data> vec[N]; 
int h[N], st[N], en[N], timedfs, up[N][20]; 
int f[N];

void pre_dfs(int u, int p) {
	st[u] = ++timedfs; 
	for (int v : g[u]) {
		if (v == p) continue; 
		h[v] = h[u] + 1; 
		up[v][0] = u; 
		for (int i = 1; i < 20; i++) {
			up[v][i] = up[up[v][i - 1]][i - 1];
		}
		pre_dfs(v, u); 
	}
	en[u] = ++timedfs; 
}

int lca(int u, int v) {
	if (h[u] != h[v]) {
		if (h[u] < h[v]) swap(u, v); 
		int k = h[u] - h[v]; 
		for (int i = 0; (1 << i) <= k; i++) {
			if ((k >> i) & 1) {
				u = up[u][i];
			} 
		}
	}
	if (u == v) return u;
	for (int i = 19; i >= 0; i--) {
		if (up[u][i] != up[v][i]) {
			u = up[u][i];
			v = up[v][i];
		}
	}
	return up[u][0];
}

void dfs(int u, int p) {
	int ans = 0; 
	for (int v : g[u]) {
		if (v == p) continue;
		dfs(v, u); 
		ans += res.get(st[v]);
	}
	for (auto &cur : vec[u]) {
		int tmp = cur.c; 
		tmp += total.get(st[cur.u]) + total.get(st[cur.v]) + f[u]; 
		tmp -= res.get(st[cur.u]) + res.get(st[cur.v]); 
		ans = max(ans, tmp); 
	}
	res.update(st[u], ans);
	res.update(en[u] + 1, -ans);
	f[p] += ans;
	total.update(st[u], f[u]);
	total.update(en[u] + 1, -f[u]); 
}

signed main(){
    ios_base::sync_with_stdio(false) ; 
    cin.tie(0) ; cout.tie(0) ; 
    if (fopen("INP.INP" ,"r")) {
        freopen("INP.INP" ,"r" , stdin) ;
        freopen("OUT.OUT" , "w" , stdout) ;
    }
    cin >> n; 
    for (int i = 1; i < n; i++) {
    	int u, v;
    	cin >> u >> v;
    	g[u].pb(v);
    	g[v].pb(u);
    }
    pre_dfs(1, 0);
    cin >> m;
    for (int i = 1; i <= m; i++) {
    	int u, v, c;
    	cin >> u >> v >> c;
    	int l = lca(u, v); 
    	vec[l].emplace_back(u, v, c);
    }
    res = BIT(2 * n);
    total = BIT(2 * n); 
    dfs(1, 0); 
    cout << res.get(st[1]); 
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:105:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |         freopen("INP.INP" ,"r" , stdin) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
election_campaign.cpp:106:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  106 |         freopen("OUT.OUT" , "w" , stdout) ;
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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