Submission #333820

#	Time	Username	Problem	Language	Result	Execution time	Memory
333820		12tqian	Mergers (JOI19_mergers)	C++17	34 / 100	3071 ms	20528 KiB

mergers

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;


int main() {
    // ios_base::sync_with_stdio(0);
    int n, k;
    cin >> n >> k;
    vector<vector<int>> adj(n);
    for (int i = 0; i < n - 1; i++) {
        int u, v; cin >> u >> v;
        u--, v--;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    vector<int> s(n);
    for (int i = 0; i < n; i++) 
        cin >> s[i], s[i]--;
    if (n == 1) {
        cout << 0 << '\n';
        return 0;
    }
    vector<int> tot(n);
    for (int x : s)
        tot[x]++;
    vector<multiset<int>> store(n);
    vector<int> id(n);
    iota(id.begin(), id.end(), 0);
    vector<int> bad(n);
    function<void(int, int)> combine = [&](int src, int par) {
        if (tot[s[src]] != 1)
            store[id[src]].insert(s[src]);
        for (int nxt : adj[src]){ 
            if (nxt == par)
                continue;
            combine(nxt, src);
            if ((int) store[id[src]].size() < (int) store[id[nxt]].size()) 
                swap(id[src], id[nxt]);
            for (int x : store[id[nxt]]) {
                store[id[src]].insert(x);
                if (store[id[src]].count(x) == tot[x])
                    store[id[src]].erase(x);
            }
        }
        if ((int) store[id[src]].size() == 0 && src != 0) 
            bad[src] = 1;
    };
    combine(0, -1);
    int amt = 0;
    for (int i = 1; i < n; i++)
        amt += bad[i];
    int leaves = 0;
    function<int(int, int)> dfs_sub = [&](int src, int par) -> int {
        int sub = bad[src];
        for (int nxt : adj[src]) {
            if (nxt == par)
                continue;
            sub += dfs_sub(nxt, src);
        }
        if (sub == 1 && bad[src]) 
            leaves++;
        else if (sub == amt && bad[src])
            leaves++;
        return sub;
    };
    dfs_sub(0, -1);
    int ans = (leaves + 1) / 2;
    cout << ans << '\n';
    return 0;
}

Compilation message (stderr)

mergers.cpp: In lambda function:
mergers.cpp:46:45: warning: comparison of integer expressions of different signedness: 'std::multiset<int>::size_type' {aka 'long unsigned int'} and '__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type' {aka 'int'} [-Wsign-compare]
   46 |                 if (store[id[src]].count(x) == tot[x])

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30