Submission #1015386

#	Time	Username	Problem	Language	Result	Execution time	Memory
1015386		Hanksburger	Election Campaign (JOI15_election_campaign)	C++17	100 / 100	163 ms	55648 KiB

election_campaign

#include <bits/stdc++.h>
using namespace std;
int par[100005][20], sum[100005][20], depth[100005], dp1[100005], dp2[100005];
vector<pair<pair<int, int>, int> > vec[100005];
vector<pair<int, int> > upd[100005];
vector<int> adj[100005];
int lca(int u, int v)
{
    if (depth[u]<depth[v])
        swap(u, v);
    int d=depth[u]-depth[v];
    for (int i=19; i>=0; i--)
        if (d&(1<<i))
            u=par[u][i];
    if (u==v)
        return u;
    for (int i=19; i>=0; i--)
    {
        if (par[u][i]!=par[v][i])
        {
            u=par[u][i];
            v=par[v][i];
        }
    }
    return par[u][0];
}
int calc(int u, int d)
{
    int res=0;
    for (int i=19; i>=0; i--)
    {
        if (d&(1<<i))
        {
            res+=sum[u][i];
            u=par[u][i];
        }
    }
    return res;
}
void dfs1(int u, int p)
{
    par[u][0]=p;
    for (int i=1; i<20; i++)
    {
        par[u][i]=par[par[u][i-1]][i-1];
        if (depth[u]-depth[par[u][i]]==(1<<i))
            upd[par[u][i]].push_back({u, i});
    }
    for (int v:adj[u])
    {
        if (v==p)
            continue;
        depth[v]=depth[u]+1;
        dfs1(v, u);
    }
}
void dfs2(int u)
{
    for (int v:adj[u])
    {
        if (v==par[u][0])
            continue;
        dfs2(v);
        dp2[u]+=dp1[v];
    }
    for (int i=0; i<upd[u].size(); i++)
    {
        int v=upd[u][i].first, x=upd[u][i].second;
        sum[v][x]=sum[v][x-1]+sum[par[v][x-1]][x-1];
    }
    dp1[u]=dp2[u];
    for (int i=0; i<vec[u].size(); i++)
    {
        int a=vec[u][i].first.first, b=vec[u][i].first.second, c=vec[u][i].second;
        dp1[u]=max(dp1[u], dp2[u]+c-calc(a, depth[a]-depth[u])-calc(b, depth[b]-depth[u]));
    }
    sum[u][0]=dp1[u]-dp2[u];
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, m;
    cin >> n;
    for (int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    dfs1(1, 1);
    cin >> m;
    for (int i=1; i<=m; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        vec[lca(a, b)].push_back({{a, b}, c});
    }
    dfs2(1);
    cout << dp1[1];
}

Compilation message (stderr)

election_campaign.cpp: In function 'void dfs2(int)':
election_campaign.cpp:66:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |     for (int i=0; i<upd[u].size(); i++)
      |                   ~^~~~~~~~~~~~~~
election_campaign.cpp:72:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<std::pair<int, int>, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |     for (int i=0; i<vec[u].size(); i++)
      |                   ~^~~~~~~~~~~~~~

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