제출 #1287195

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1287195		RiverFlow	Mergers (JOI19_mergers)	C++20	100 / 100	636 ms	110064 KiB

mergers

#include <bits/stdc++.h>

#define nl "\n"
#define no "NO"
#define yes "YES"
#define fi first
#define se second
#define vec vector
#define task "main"
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
#define unq(x) sort(all(x)); x.resize(unique(all(x)) - x.begin())

using namespace std;

template<typename U, typename V> bool maxi(U &a, V b) {
    if (a < b) { a = b; return 1; } return 0;
}
template<typename U, typename V> bool mini(U &a, V b) {
    if (a > b) { a = b; return 1; } return 0;
}

const int N = (int)5e5 + 9;
const int mod = (int)1e9 + 7;

void prepare(); void main_code();

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    const bool MULTITEST = 0; prepare();
    int num_test = 1; if (MULTITEST) cin >> num_test;
    while (num_test--) { main_code(); }
}

void prepare() {};

int par[N], h[N];
int p[N], z[N], high[N];

vector<int> adj[N];
vector<int> r[N];

void dfs(int u, int p) {
    for(int v : adj[u]) if (v != p) {
        h[v] = h[u] + 1;
        par[v] = u;
        dfs(v, u);
    }
}


int root(int u) {
    return u == p[u] ? u : p[u] = root(p[u]);
}
void unite(int u, int v) {
    u=root(u), v=root(v);
//    cerr << "u,v: " << u << ' ' << v << nl;
    if (z[u] < z[v]) swap(u, v);
    z[u] += z[v], high[u] = (h[high[u]] < h[high[v]] ? high[u] : high[v]);
    p[v] = u;
}
void unite2(int u, int v) {
//    cerr << u << ' ' << v << nl;
    u = root(u), v = root(v);
    if (u == v) return ;

    u = high[u], v = high[v];

    if (h[u] == h[v]) {
        unite2(par[u], par[v]);
        unite(u, par[u]);
        unite(v, par[v]);
        return ;
    }

    if (h[u] < h[v]) swap(u, v);
    unite2(par[u], v);
    unite(u, par[u]);
}

vector<int> adj2[N];

void main_code() {
    int n, k; cin >> n >> k;
    FOR(i, 1, n - 1) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for(int i = 1; i <= n; ++i) {
        int x; cin >> x; r[x].push_back(i);
    }
    FOR(i, 1, n) p[i] = i, high[i] = i, z[i] = 1;

    dfs(1, 0);

    FOR(i, 1, k) {
        for(int j = 0; j + 1 < sz(r[i]); ++j) {
            unite2(r[i][j], r[i][j + 1]);
        }
    }
    int ans = 0;
    FOR(i, 1, n) {
        for(int j : adj[i]) if (i < j) {
            if (root(i) != root(j)) {
                adj2[root(i)].push_back(root(j));
                adj2[root(j)].push_back(root(i));
            }
        }
    }
    FOR(i, 1, n) {
        unq(adj2[i]);
        ans += adj2[i].size() == 1;
    }
    cout << (ans + 1) / 2;
}


/*     Let the river flows naturally     */

컴파일 시 표준 에러 (stderr) 메시지

mergers.cpp: In function 'int main()':
mergers.cpp:36:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mergers.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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