Submission #963237

#	Time	Username	Problem	Language	Result	Execution time	Memory
963237		BhavayGoyal	Election Campaign (JOI15_election_campaign)	C++14	10 / 100	121 ms	42812 KiB

election_campaign

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<class T> using oset = 
            tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define ll long long
#define ld long double
#define ar array
#define vi vector<int>
#define vii vector<vector<int>>
#define pii pair<int, int>
#define pb push_back
#define all(x) x.begin(), x.end()
#define f first
#define s second
#define endl "\n"

const int MOD = 1e9+7;
const int inf = 1e9;
const ll linf = 1e18;

const int d4i[4]={-1, 0, 1, 0}, d4j[4]={0, 1, 0, -1};
const int d8i[8]={-1, -1, 0, 1, 1, 1, 0, -1}, d8j[8]={0, 1, 1, 1, 0, -1, -1, -1};

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());


// -------------------------------------------------- Main Code --------------------------------------------------

struct fenTree {
    int n;
    vi tree;

    fenTree(int N) {n = N+5; tree = vi(n+5);}

    void update(int idx, int val) {for (idx; idx <= n; idx += (idx&-idx)) tree[idx] += val;}
    int sum(int idx) {int ans = 0; for (idx; idx; idx -= (idx&-idx)) ans += tree[idx]; return ans;}
};

const int N = 1e5+5;
vi g[N];
int parent[N][25], tin[N], tout[N], Time = 0, depth[N], dp[N][2];
vector<array<int, 3>> arr[N];
fenTree Tree(N);

void dfs2(int src, int par) {
    tin[src] = ++Time;
    parent[src][0] = par;
    for (int j = 1; j < 25; j++) parent[src][j] = parent[parent[src][j-1]][j-1];
    for (auto ch : g[src]) {
        if (ch == par) continue;
        depth[ch] = depth[src]+1;
        dfs2(ch, src);
    }
    tout[src] = ++Time;
}


int lca(int a, int b) {
    if (depth[a] > depth[b]) swap(a, b);
    int diff = depth[b]-depth[a];
    for (int j = 0; j < 25; j++) {
        if (diff&(1<<j)) b = parent[b][j];
    }

    for (int j = 24; j >= 0; j--) if (parent[a][j] != parent[b][j]) a = parent[a][j], b = parent[b][j];

    if (a == b) return a;

    return parent[a][0];
}

void dfs(int src, int par) {
    for (auto ch : g[src]) {
        if (ch == par) continue;
        dfs(ch, src);
        dp[src][0] += dp[ch][1];
    }

    dp[src][1] = dp[src][0];
    for (auto x : arr[src]) {
        int a = x[0], b = x[1], votes = x[2];
        dp[src][1] = max(dp[src][1], dp[src][0] + Tree.sum(tin[a]) + Tree.sum(tin[b]) + votes);
    }

    Tree.update(tin[src], dp[src][0]-dp[src][1]);
    Tree.update(tout[src], dp[src][1]-dp[src][0]);
}

void sol() {
    int n; cin >> n;
    for (int i = 1; i <= n-1; i++) {
        int a, b; cin >> a >> b;
        g[a].pb(b);
        g[b].pb(a);
    }

    dfs2(1, -1);

    int m; cin >> m;
    for (int i = 1; i <= m; i++) {
        int a, b, c; cin >> a >> b >> c;
        int l = lca(a, b);
        arr[l].pb({a, b, c});
    }

    dfs(1, -1);

    cout << max(dp[1][0], dp[1][1]) << endl;
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int t = 1;
    // cin >> t; 
    while (t--) {
        sol();
    }
    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In member function 'void fenTree::update(int, int)':
election_campaign.cpp:41:41: warning: statement has no effect [-Wunused-value]
   41 |     void update(int idx, int val) {for (idx; idx <= n; idx += (idx&-idx)) tree[idx] += val;}
      |                                         ^~~
election_campaign.cpp: In member function 'int fenTree::sum(int)':
election_campaign.cpp:42:41: warning: statement has no effect [-Wunused-value]
   42 |     int sum(int idx) {int ans = 0; for (idx; idx; idx -= (idx&-idx)) ans += tree[idx]; return ans;}
      |                                         ^~~

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