Submission #571667

#	Time	Username	Problem	Language	Result	Execution time	Memory
571667		YouAreMyGalaxy	Mergers (JOI19_mergers)	C++17	100 / 100	1077 ms	135628 KiB

mergers

//Make CSP great again
//Vengeance
#include <bits/stdc++.h>
#define TASK "TESTCODE"
#define Log2(x) 31 - __builtin_clz(x)
using namespace std;
const int N = 5e5, cbit = 18;
vector<int> num[N + 1], adj[N + 1];
int n, k, tin[N + 1], tout[N + 1], depth[N + 1], dp[N + 1], timer, res, cnt[N + 1], f[N + 1][cbit + 1];
void read()
{
    cin >> n >> k;
    for (int i = 1; i < n; ++ i)
    {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int u = 1; u <= n; ++ u)
    {
        int a;
        cin >> a;
        num[a].push_back(u);
    }
}
void preDFS(int u, int p)
{
    tin[u] = ++timer;
    for (int v : adj[u])
    {
        if (v == p)
        {
            continue;
        }
        depth[v] = depth[u] + 1;
        f[v][0] = u;
        for (int i = 1; i <= cbit; ++ i)
        {
            f[v][i] = f[f[v][i - 1]][i - 1];
            if (!f[v][i])
            {
                break;
            }
        }
        preDFS(v, u);
    }
    tout[u] = timer;
}
int LCA(int u, int v)
{
    if (depth[u] > depth[v])
    {
        swap(u, v);
    }
    int k = depth[v] - depth[u];
    for (int i = cbit; i >= 0; -- i)
    {
        if ((k >> i) & 1)
        {
            v = f[v][i];
        }
    }
    if (u == v)
    {
        return u;
    }
    for (int i = cbit; i >= 0; -- i)
    {
        if (f[u][i] != f[v][i])
        {
            u = f[u][i];
            v = f[v][i];
        }
    }
    return f[u][0];
}
void DFS_down(int u, int p)
{
    for (int v : adj[u])
    {
        if (v == p)
        {
            continue;
        }
        DFS_down(v, u);
        dp[u] += dp[v];
    }
}
void DFS(int u, int p, int last_zero)
{
    if (dp[u] == 0)
    {
        if (last_zero != -1)
        {
            ++cnt[last_zero];
            ++cnt[u];
        }
        last_zero = u;
    }
    for (int v : adj[u])
    {
        if (v == p)
        {
            continue;
        }
        DFS(v, u, last_zero);
    }
}
void solve()
{
    preDFS(1, 0);
    for (int i = 1; i <= k; ++ i)
    {
        sort(num[i].begin(), num[i].end(), [&](const int &x, const int &y)
             {
                 return tin[x] < tin[y];
             });
        vector<int> add, tmp;
        stack<int> st;
        for (int j = 1; j < num[i].size(); ++ j)
        {
            add.push_back(LCA(num[i][j], num[i][j - 1]));
        }
        move(add.begin(), add.end(), back_inserter(num[i]));
        sort(num[i].begin(), num[i].end(), [&](const int &x, const int &y)
             {
                 return tin[x] < tin[y];
             });
        num[i].erase(unique(num[i].begin(), num[i].end()), num[i].end());
        for (int u : num[i])
        {
            while(!st.empty() && (tin[u] < tin[st.top()] || tin[u] > tout[st.top()]))
            {
                st.pop();
            }
            if (!st.empty())
            {
                ++dp[st.top()];
                --dp[u];
            }
            st.push(u);
        }
    }
    DFS_down(1, 0);
    DFS(1, 0, -1);
    for (int u = 1; u <= n; ++ u)
    {
        res += (cnt[u] == 1);
    }
    cout << (res + 1)/2;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".OUT", "w", stdout);
    }
    int t = 1;
    bool typetest = false;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        //cout << "Case #" << __ << ":" << '\n';
        read();
        solve();
    }
}

Compilation message (stderr)

mergers.cpp: In function 'void solve()':
mergers.cpp:121:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  121 |         for (int j = 1; j < num[i].size(); ++ j)
      |                         ~~^~~~~~~~~~~~~~~
mergers.cpp: In function 'int main()':
mergers.cpp:159:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  159 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30