Submission #1039170

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039170		Tonyl	Spring cleaning (CEOI20_cleaning)	C++17	100 / 100	121 ms	19808 KiB

cleaning

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
#define REP(i,n) for (int i = 0; i < n; i++)
#define trav(a,x) for (auto &a : x)
#define all(x) (x).begin(), (x).end()
#define submit(a,b) cout << a << " " << b << endl
#define D(x) //cerr << #x << ": " << x << endl;

const int MAX_N = 2e5;
int n,q;

vector<vi> graph;
vi children;

int total = 0;
int nonleaf = 0;

bool rtr[MAX_N];
bool is_leaf[MAX_N];
int parent[MAX_N];

int top[MAX_N];
int hv[MAX_N];
int subtr[MAX_N];
int ind[MAX_N];

bool rawr[MAX_N];

int pref[MAX_N];

void dfs1(int i, int par = -1) {
    int &sub = subtr[i];
    sub = 1;

    trav(nei, graph[i]) {
        if (nei == par) continue;
        dfs1(nei, i);
        sub += subtr[nei];
    }
}

int id = 0;
void dfs2(int i, int par = -1, int head = nonleaf) {
    top[i] = head;
    ind[i] = id++;
    int heaviest = -1;
    int mass = 0;

    trav(nei, graph[i]) {
        if (nei == par) continue;
        if (subtr[nei] > mass) {
            mass = subtr[nei];
            heaviest = nei;
        }
    }

    if (heaviest == -1) return;

    dfs2(heaviest, i, head);
    
    trav(nei, graph[i]) {
        if (nei == par) continue;
        if (nei == heaviest) continue;
        dfs2(nei, i, nei);
    }
}

int calc(int i, int par = -1) {
    if (par == -1) total = 0;
    parent[i] = par;

    int fr = 0;
    trav(nei, graph[i]) {
        if (nei == par) continue;
        int o = calc(nei, i);
        total += o; fr += o;
    }
    fr += children[i]; total += children[i];
    if (fr == 0) {fr = 1; is_leaf[i] = 1;}

    if (fr > 2) fr = 2 - (fr%2);

    rtr[i] = fr == 1;
    rawr[ind[i]] = fr == 1;
    return fr;
}

vector<vi> bots;
vi to_check;
void flip(int i, bool rev=false) {
    while (i != -1) {
        D(i);

        if (rev) children[i]--;

        if (is_leaf[i] && children[i] == 0) {
            if (!rev) children[i]++;
            return;
        }
        if (!rev) children[i]++;

        if (top[i] == i) {
            if (i != nonleaf) {
                if (!rtr[i]) total--;
                else total++;
            }
            rtr[i] = !rtr[i];
            i = parent[i];
        } else {
            bots[top[i]].push_back(ind[i]);
            to_check.push_back(top[i]);
            i = top[i];
        }

        D(total);
    }
}

void exec_heavy() {
    trav(check, to_check) {
        D(check);
        if (bots[check].size() == 0) continue;

        sort(all(bots[check]));

        vi bts;
        trav(bot, bots[check]) {
            if (bts.size() && bts.back() == bot) bts.pop_back();
            else bts.push_back(bot);
        }

        bool flp = bts.size()%2;

        int prev = ind[check];
        trav(bot, bts) {
            D(bot);

            int ones = pref[bot+1]-pref[prev+1];
            int twos = (bot-prev) - ones;

            D(total);
            D(ones); D(twos);
            if (flp) {
                total += ones;
                total -= twos;
            }
            D(total);

            prev = bot;
            flp = !flp;
        }

        bots[check] = vi();
    }
    to_check = vi();
}

void make_graph() {
    graph.assign(n, vi());
    REP(i,n-1) {
        int u,v; cin >> u >> v; u--; v--;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    children.assign(n, 0);
    bots.assign(n, vi());

    REP(i,n) {
        if (graph[i].size() > 1) {nonleaf = i; break;}
    }

    dfs1(nonleaf); dfs2(nonleaf);
    calc(nonleaf);

    REP(i,n) {
        pref[i+1] = pref[i] + rawr[i];
    }

    D(total);
}

int query() {
    int d; cin >> d;
    D(d);
    vi added;
    int prv = total;

    REP(dd, d) {
        int a; cin >> a; a--;
        added.push_back(a);
        flip(a);
    }
    exec_heavy();

    int tot = total;
    bool frb = rtr[nonleaf];

    trav(a, added) flip(a, 1);
    exec_heavy();
    total = prv;

    if (frb) return -1;
    else return tot+d;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    cin >> n >> q;
    make_graph();

    REP(qq, q) {
        cout << query() << "\n";
    }
}

• 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