Submission #968549

#	Time	Username	Problem	Language	Result	Execution time	Memory
968549		Neco_arc	Election Campaign (JOI15_election_campaign)	C++17	100 / 100	117 ms	39876 KiB

election_campaign

#include <bits/stdc++.h>

#define ll long long
#define fi(i, a, b) for(int i = a; i <= b; i++)
#define fid(i, a, b) for(int i = a; i >= b; i--)
#define maxn (int) 2e5 + 7

using namespace std;

int n, m;
int cha[maxn][20];
ll dp[maxn], Sum[maxn];
struct dl { int x, y, w; } a[maxn];
vector<int> edges[maxn], store[maxn];

int In[maxn], Out[maxn];
void pre_dfs(int u, int par) {
    static int Time = 0;
    In[u] = ++Time;
    for(int v : edges[u]) if(v != par) {
        cha[v][0] = u;
        fi(i, 1, 17) cha[v][i] = cha[cha[v][i - 1]][i - 1];
        pre_dfs(v, u);
    }
    Out[u] = Time;
}

bool insubtree(int u, int p) { return p == 0 || In[p] <= In[u] && In[u] <= Out[p]; }

int lca(int u, int v) {
    if(insubtree(u, v)) return v;
    if(insubtree(v, u)) return u;
    fid(i, 17, 0) if(!insubtree(v, cha[u][i])) u = cha[u][i];
    return cha[u][0];
}

struct BIT {
    ll bit[maxn];
    void update(int l, int r, ll val) {
        for(; l < maxn; l += (l & -l)) bit[l] += val;
        for(++r; r < maxn; r += (r & -r)) bit[r] -= val;
    }
    ll get(int x, ll ans = 0) {
        for(; x > 0; x -= (x & -x)) ans += bit[x];
        return ans;
    }
} Bit;

void dfs(int u, int par)
{
    for(int v : edges[u]) if(v != par) dfs(v, u), Sum[u] += dp[v];
    dp[u] = Sum[u];

    for(int id : store[u]) {
        ll val = a[id].w;
        if(a[id].x != u) val += Bit.get(In[a[id].x]);
        if(a[id].y != u) val += Bit.get(In[a[id].y]);

        dp[u] = max(dp[u], Sum[u] + val);
    }
    Bit.update(In[u], Out[u], Sum[u] - dp[u]);
}

int main()
{

    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    cin >> n;
    fi(i, 1, n - 1) {
        int x, y; cin >> x >> y;
        edges[x].push_back(y), edges[y].push_back(x);
    }

    pre_dfs(1, 0);

    cin >> m;
    fi(i, 1, m) {
        int x, y, w; cin >> x >> y >> w;
        store[lca(x, y)].push_back(i);
        a[i] = {x, y, w};
    }

    dfs(1, 0);
    cout << dp[1];

    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'bool insubtree(int, int)':
election_campaign.cpp:28:64: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   28 | bool insubtree(int u, int p) { return p == 0 || In[p] <= In[u] && In[u] <= Out[p]; }
      |                                                 ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~

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