Submission #1039119

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039119		Tonyl	Spring cleaning (CEOI20_cleaning)	C++17	28 / 100	1065 ms	10328 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 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;
    return fr;
}

void flip(int i, bool rev=false) {
    while (i != -1) {
        D(i);
        if (parent[i] != -1) {
            if (rev) children[i]--;

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

            if (!rev) children[i]++;
        }
        D(total);

        rtr[i] = !rtr[i];
        i = parent[i];
    }
}

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);

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

    calc(nonleaf);
    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);
    }
    int tot = total;
    bool frb = rtr[nonleaf];

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

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