Submission #755682

#	Time	Username	Problem	Language	Result	Execution time	Memory
755682		Desh03	Election Campaign (JOI15_election_campaign)	C++17	10 / 100	144 ms	33248 KiB

election_campaign

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

vector<int> dep, dp, dp2;
vector<vector<int>> g, up;
vector<vector<tuple<int, int, int>>> qr;
int t, lg;

void dfs(int u, int p) {
    up[0][u] = p;
    for (int i = 1; i < lg; i++) up[i][u] = up[i - 1][up[i - 1][u]];
    for (int v : g[u])
        if (v ^ p)
            dep[v] = dep[u] + 1, dfs(v, u);
}

int getkth(int u, int k) {
    for (int i = 0; i < lg; i++)
        if (k >> i & 1)
            u = up[i][u];
    return u;
}

void calc_dp(int u, int p) {
    for (int v : g[u])
        if (v ^ p) {
            calc_dp(v, u);
            dp2[u] += dp[v];
        }
    dp[u] = dp2[u];
    for (auto [x, y, w] : qr[u]) {
        int c1 = getkth(x, dep[x] - dep[u] - 1);
        int c2 = getkth(y, dep[y] - dep[u] - 1);
        int cost = w + dp2[x] + dp2[y] + dp2[u];
        if (x ^ u) cost -= dp[c1];
        else cost -= dp2[u];
        if (y ^ u) cost -= dp[c2];
        else cost -= dp2[u];
        dp[u] = max(dp[u], cost);
    }
}

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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    while ((1 << lg) <= n) ++lg;
    g.resize(n), up = vector<vector<int>> (lg, vector<int> (n)), dp.resize(n), dp2.resize(n), dep.resize(n), qr.resize(n);
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(0, 0);
    int q;
    cin >> q;
    while (q--) {
        int u, v, w;
        cin >> u >> v >> w;
        --u, --v;
        qr[lca(u, v)].push_back({u, v, w});
    }
    calc_dp(0, 0);
    cout << dp[0] << '\n';
}

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