Submission #718957

#	Time	Username	Problem	Language	Result	Execution time	Memory
718957		walterw	Mergers (JOI19_mergers)	C++17	100 / 100	669 ms	91888 KiB

mergers

#include "bits/stdc++.h"

using namespace std;

void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
    cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
    while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
    return o >> a.first >> a.second;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
    return o << '(' << a.first << ", " << a.second << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
    bool is = false;
    for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
    return o << '}';
}

#ifdef local
#define test(args...) abc("[" + string(#args) + "]", args)
#else
#define test(args...) void(0)
#endif

using ll = long long;

vector<int> adj[500005];
int par[500005];
vector<int> group[500005];
int depth[500005];

void dfs(int node, int parr = -1) {
    for (auto nxt : adj[node]) {
        if (nxt == parr) continue;

        par[nxt] = node;
        depth[nxt] = depth[node] + 1;
        dfs(nxt, node);
    }
}

int pr[500005];
int deg[500005];

int findset(int i) {
    if (pr[i] == i) return i;
    return pr[i] = findset(pr[i]);
}

void merge(int a, int b) {
    while (a != b) {
        if (depth[a] < depth[b]) swap(a, b);
        pr[a] = findset(par[a]);
        a = pr[a];
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
//    freopen("", "r", stdin);
//    freopen("", "w", stdout);
    int n, k; cin >> n >> k;
    for (int i = 0; i < n - 1; i++) {
        int a, b; cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    for (int i = 1; i <= n; i++) pr[i] = i;

    for (int i = 1; i <= n; i++) {
        int temp; cin >> temp;
        group[temp].push_back(i);
    }

    depth[1] = 1;
    dfs(1);

    for (int i = 1; i <= n; i++) {
        if (group[i].empty()) continue;

        for (int j = 1; j < group[i].size(); j++) {
            merge(group[i][0], group[i][j]);
        }
    }

    for (int i = 1; i <= n; i++) {
        for (auto j : adj[i]) {
            if (findset(i) != findset(j)) {
                deg[findset(i)]++;
                deg[findset(j)]++;
            }
        }
    }

    int ct = 0;

    for (int i = 1; i <= n; i++) {
        if (deg[i] == 2) ct++;
    }
    cout << (ct + 1) / 2;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:88:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |         for (int j = 1; j < group[i].size(); j++) {
      |                         ~~^~~~~~~~~~~~~~~~~

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