Submission #1146199

#	Time	Username	Problem	Language	Result	Execution time	Memory
1146199		kh0i	Spring cleaning (CEOI20_cleaning)	C++20	100 / 100	119 ms	17988 KiB

cleaning

#include "bits/stdc++.h"
using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif

using ll = long long;
using pii = pair<int, int>;

#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
    assert(l <= r);
    return uniform_int_distribution<ll> (l, r)(rng);
}

const int N = 1e5 + 3;

int n, q, root;
vector<int> g[N];
int leaf[N];
bool is_leaf[N];
int pos[N], p[N], head[N], cur_pos, h[N], sz[N];

namespace ST{
    int st[N << 2], lz[N << 2];

    void flip_node(int id, int l, int r){
        lz[id] ^= 1;
        st[id] = (r - l + 1) - st[id];
    }

    void down(int id, int l, int r){
        int mid = (l + r) >> 1;
        flip_node(id << 1, l, mid);
        flip_node(id << 1 | 1, mid + 1, r);
        lz[id] = 0;
    }

    void update(int pos, int val, int id = 1, int l = 1, int r = n){
        if(l == r){
            st[id] = val;
            return;
        }
        int mid = (l + r) >> 1;
        if(pos <= mid)
            update(pos, val, id << 1, l, mid);
        else
            update(pos, val, id << 1 | 1, mid + 1, r);
        st[id] = st[id << 1] + st[id << 1 | 1];
    }

    void flip(int tl, int tr, int id = 1, int l = 1, int r = n){
        if(l > tr or tl > r)
            return;
        if(tl <= l and r <= tr){
            flip_node(id, l, r);
            return;
        }
        int mid = (l + r) >> 1;
        if(lz[id])
            down(id, l, r);
        flip(tl, tr, id << 1, l, mid);
        flip(tl, tr, id << 1 | 1, mid + 1, r);
        st[id] = st[id << 1] + st[id << 1 | 1];
    }
}

void dfs(int u, int pre = -1){
    is_leaf[u] = (sz(g[u]) == 1);
    leaf[u] = is_leaf[u];
    sz[u] = 1;
    for(int v : g[u]){
        if(v == pre)
            continue;
        h[v] = h[u] + 1;
        p[v] = u;
        dfs(v, u);
        sz[u] += sz[v];
        leaf[u] += leaf[v];
    }
}

void hld(int u, int cur_head, int pre = -1){
    pos[u] = ++cur_pos;
    head[u] = cur_head;
    int nx = -1;
    for(int v : g[u])
        if(v != pre and (nx == -1 or sz[nx] < sz[v]))
            nx = v;
    if(nx != -1)
        hld(nx, cur_head, u);
    for(int v : g[u])
        if(v != pre and v != nx)
            hld(v, v, u);
}

void flip(int u){
    while(head[u] != root){
        ST::flip(pos[head[u]], pos[u]);
        u = p[head[u]];
    }
    ST::flip(2, pos[u]);
}

void solve(){
    cin >> n >> q;
    for(int i = 1; i < n; ++i){
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    for(int i = 1; i <= n; ++i){
        if(sz(g[i]) > 1){
            root = i;
            break;
        }
    }

    dfs(root);
    hld(root, root);

    for(int i = 1; i <= n; ++i)
        if(i != root)
            ST::update(pos[i], leaf[i] % 2 == 0);

    while(q--){
        int d;
        cin >> d;

        int cnt = leaf[root] + d;
        vector<int> old_leaf, changed;
        for(int i = 1; i <= d; ++i){
            int a;
            cin >> a;
            if(is_leaf[a]){
                is_leaf[a] = 0, --cnt;
                old_leaf.push_back(a);
            }
            else{
                changed.push_back(a);
                flip(a);
            }
        }

        if(cnt & 1)
            cout << -1 << '\n';
        else
            cout << n - 1 + d + ST::st[1] << '\n';   

        for(int i : old_leaf)
            is_leaf[i] = 1;
        for(int i : changed)
            flip(i);
    }
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(0);
    #define task "troll"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
//    cin >> test;
    for(int i = 1; i <= test; ++i){
//        cout << "Case #" << i << ": ";
        solve();
    }
    #ifdef LOCAL
        cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    return 0;
}

Compilation message (stderr)

cleaning.cpp: In function 'int32_t main()':
cleaning.cpp:171:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  171 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:172:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  172 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 17 / 17
• Subtask 7: 30 / 30