Submission #672499

#	Time	Username	Problem	Language	Result	Execution time	Memory
672499		tamthegod	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	511 ms	41932 KiB

election_campaign

// Make the best become better
// No room for laziness
#include<bits/stdc++.h>
 
#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n, m;
vector<int> adj[maxN];
struct TPath
{
    int s, t, w;
} a[maxN];
int sz[maxN], p[maxN], depth[maxN];
int chainhead[maxN], chainid[maxN], nChain = 0;
int timein[maxN], Time = 0;
vector<TPath> vc[maxN];
int f[maxN];
struct SegTree
{
    int st[4 * maxN];
    void Init()
    {
        memset(st, 0, sizeof st);
    }
    void update(int id, int l, int r, int pos, int val)
    {
        if(l > pos || r < pos) return;
        if(l == r && l == pos)
        {
            st[id] += val;
            return;
        }
        int mid = (l + r) / 2;
        update(id * 2, l, mid, pos, val);
        update(id * 2 + 1, mid + 1, r, pos, val);
        st[id] = st[id * 2] + st[id * 2 + 1];
    }
    int get(int id, int l, int r, int u, int v)
    {
        if(l > v || r < u) return 0;
        if(l >= u && r <= v) return st[id];
        int mid = (l + r) / 2;
        return get(id * 2, l, mid, u, v) + get(id * 2 + 1, mid + 1, r, u, v);
    }
} tree1, tree2;
void dfs(int u)
{
    sz[u] = 1;
    for(int v : adj[u])
    {
        if(v == p[u]) continue;
        p[v] = u;
        depth[v] = depth[u] + 1;
        dfs(v);
        sz[u] += sz[v];
    }
}
 
void HLD(int u)
{
    if(!chainhead[nChain]) chainhead[nChain] = u;
    chainid[u] = nChain;
    timein[u] = ++Time;
    int bigChild = -1;
    for(int v : adj[u])
    {
        if(v == p[u]) continue;
        if(bigChild == -1 || sz[bigChild] < sz[v]) bigChild = v;
    }
    if(bigChild != -1) HLD(bigChild);
    for(int v : adj[u])
    {
        if(v == p[u] || v == bigChild) continue;
        nChain++;
        HLD(v);
    }
}
int LCA(int u, int v)
{
    while(chainhead[chainid[u]] != chainhead[chainid[v]])
    {
        if(depth[chainhead[chainid[u]]] < depth[chainhead[chainid[v]]]) swap(u, v);
        u = p[chainhead[chainid[u]]];
    }
    if(depth[u] > depth[v]) swap(u, v);
    return u;
}
int Query(int u, int v)
{
    int res = 0;
    while(chainhead[chainid[u]] != chainhead[chainid[v]])
    {
        if(depth[chainhead[chainid[u]]] < depth[chainhead[chainid[v]]]) swap(u, v);
        res += tree1.get(1, 1, n, timein[chainhead[chainid[u]]], timein[u]);
        u = p[chainhead[chainid[u]]];
    }
    if(depth[u] > depth[v]) swap(u, v);
    res += tree1.get(1, 1, n, timein[u], timein[v]);
    return res;
}
int Query1(int u, int v)
{
    int res = 0;
    while(chainhead[chainid[u]] != chainhead[chainid[v]])
    {
        if(depth[chainhead[chainid[u]]] < depth[chainhead[chainid[v]]]) swap(u, v);
        res += tree2.get(1, 1, n, timein[chainhead[chainid[u]]], timein[u]);
        u = p[chainhead[chainid[u]]];
    }
    if(depth[u] > depth[v]) swap(u, v);
    res += tree2.get(1, 1, n, timein[u], timein[v]);
    return res;
}
void ReadInput()
{
    cin >> n;
    for(int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    cin >> m;
    for(int i=1; i<=m; i++)
    {
        cin >> a[i].s >> a[i].t >> a[i].w;
    }
}
void DFS(int u)
{
    int sum = 0;
    for(int v : adj[u])
    {
        if(v == p[u]) continue;
        DFS(v);
        sum += f[v];
    }
    f[u] = sum;
    for(int v : adj[u])
    {
        if(v == p[u]) continue;
        tree1.update(1, 1, n, timein[u], f[v]);
    }
    for(TPath a : vc[u])
    {
        f[u] = max(f[u], Query(a.s, a.t) - Query1(a.s, a.t) + a.w);
    }
    tree2.update(1, 1, n, timein[u], f[u]);
}
void Solve()
{
    dfs(1);
    HLD(1);
    tree1.Init();
    tree2.Init();
    for(int i=1; i<=m; i++)
       vc[LCA(a[i].s, a[i].t)].pb(a[i]);
    DFS(1);
    cout << f[1];
}
int32_t main()
{
    //freopen("x.inp", "r", stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ReadInput();
    Solve();
}

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