Submission #667936

#	Time	Username	Problem	Language	Result	Execution time	Memory
667936		stevancv	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	177 ms	32856 KiB

election_campaign

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e5 + 2;
const int inf = 2e9;
vector<int> g[N];
int par[N][17], in[N], out[N], tsz;
void Dfs(int s, int e) {
    in[s] = ++tsz;
    par[s][0] = e;
    for (int i = 1; i < 17; i++) par[s][i] = par[par[s][i - 1]][i - 1];
    for (int u : g[s]) {
        if (u != e) Dfs(u, s);
    }
    out[s] = ++tsz;
}
bool Ancestor(int u, int v) {
    return in[u] <= in[v] && out[v] <= out[u];
}
int Lca(int u, int v) {
    if (Ancestor(u, v)) return u;
    if (Ancestor(v, u)) return v;
    for (int i = 16; i >= 0; i--) {
        if (par[u][i] && !Ancestor(par[u][i], v)) u = par[u][i];
    }
    return par[u][0];
}
ll dp[N], sum[N];
vector<array<int, 3>> paths[N];
struct fenwick {
    ll bit[2 * N];
    void Add(int x, ll v) {
        for (; x < 2 * N; x += x & (-x)) bit[x] += v;
    }
    ll P(int x) {
        ll ans = 0;
        for (; x > 0; x -= x & (-x)) ans += bit[x];
        return ans;
    }
    ll Get(int l, int r) {
        if (l > r) return 0;
        return P(r) - P(l - 1);
    }
}f1, f2;
void Dfs1(int s, int e) {
    for (int u : g[s]) {
        if (u == e) continue;
        Dfs1(u, s);
        sum[s] += dp[u];
    }
    dp[s] = sum[s];
    f1.Add(in[s], sum[s]); f1.Add(out[s], -sum[s]);
    for (auto u : paths[s]) {
        int a = u[0]; int b = u[1]; int c = u[2];
        smax(dp[s], f1.Get(in[s], in[a]) + f1.Get(in[s] + 1, in[b]) - f2.Get(in[s] + 1, in[a]) - f2.Get(in[s] + 1, in[b]) + c);
    }
    f2.Add(in[s], dp[s]); f2.Add(out[s], -dp[s]);
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n; cin >> n;
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    Dfs(1, 0);
    int m; cin >> m;
    for (int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        paths[Lca(a, b)].push_back({a, b, c});
    }
    Dfs1(1, 0);
    cout << dp[1] << en;
    return 0;
}

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