Submission #782300

#	Time	Username	Problem	Language	Result	Execution time	Memory
782300		borisAngelov	Cat Exercise (JOI23_ho_t4)	C++17	0 / 100	3 ms	5076 KiB

Main

#include <bits/stdc++.h>

using namespace std;

const int maxn = 200005;
const int max_log = 18;
const int inf = 1000000000;

int n;

vector<int> g[maxn];

int depth[maxn];
long long dp[maxn];

int permutation[maxn];

int jump[maxn][max_log];

void dfs(int node, int par, int dep)
{
    depth[node] = dep;

    for (auto next_node : g[node])
    {
        if (next_node != par)
        {
            jump[next_node][0] = node;
            dfs(next_node, node, dep + 1);
        }
    }
}

void build_sparse()
{
    jump[1][0] = 1;

    for (int i = 1; i <= max_log - 1; ++i)
    {
        for (int j = 1; j <= n; ++j)
        {
            jump[j][i] = jump[jump[j][i - 1]][i - 1];
        }
    }
}

int find_lca(int x, int y)
{
    if (depth[x] < depth[y])
    {
        swap(x, y);
    }

    int diff = depth[x] - depth[y];

    for (int i = 0; i <= max_log - 1; ++i)
    {
        if ((diff & (1 << i)) != 0)
        {
            x = jump[x][i];

            diff -= (1 << i);

            if (diff == 0)
            {
                break;
            }
        }
    }

    if (x == y)
    {
        return x;
    }

    for (int i = max_log - 1; i >= 0; --i)
    {
        if (jump[x][i] != jump[y][i])
        {
            x = jump[x][i];
            y = jump[y][i];
        }
    }

    return jump[x][0];
}

int find_dist(int x, int y)
{
    return depth[x] + depth[y] - 2 * depth[find_lca(x, y)];
}

int parent[maxn];
int dsu_rank[maxn];
int component_current_root[maxn];

int find_root(int node)
{
    if (parent[node] == node)
    {
        return node;
    }

    return parent[node] = find_root(parent[node]);
}

void connect(int x, int y)
{
    x = find_root(x);
    y = find_root(y);

    if (x == y)
    {
        return;
    }

    if (dsu_rank[x] < dsu_rank[y])
    {
        swap(x, y);
    }

    if (dsu_rank[x] == dsu_rank[y])
    {
        ++dsu_rank[y];
    }

    parent[y] = x;
}

void fastIO()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int main()
{
    fastIO();

    cin >> n;

    for (int i = 1; i <= n; ++i)
    {
        cin >> permutation[i];
    }

    for (int i = 1; i <= n - 1; ++i)
    {
        int x, y;
        cin >> x >> y;

        x = permutation[x];
        y = permutation[y];

        g[x].push_back(y);
        g[y].push_back(x);
    }

    dfs(1, -1, 0);

    for (int i = 1; i <= n; ++i)
    {
        dsu_rank[i] = 1;
        parent[i] = i;
        component_current_root[i] = i;
    }

    for (int node = 1; node <= n; ++node)
    {
        for (auto next_node : g[node])
        {
            if (next_node > node)
            {
                continue;
            }

            dp[node] = max(dp[node], dp[component_current_root[find_root(next_node)]] + find_dist(node, component_current_root[find_root(next_node)]));

            connect(node, next_node);
        }

        component_current_root[find_root(node)] = node;
    }

    cout << dp[n] << endl;

    return 0;
}

• Subtask 1: 0 / 7
• Subtask 2: 0 / 7
• Subtask 3: 0 / 7
• Subtask 4: 0 / 10
• Subtask 5: 0 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26