Submission #1271458

#	Time	Username	Problem	Language	Result	Execution time	Memory
1271458		red_souls	Spring cleaning (CEOI20_cleaning)	C++20	0 / 100	1096 ms	9080 KiB

cleaning

#include <bits/stdc++.h>
#define ll long long
#define int long long
#define task "crt"
using namespace std;

const int N = 2e5 + 16;
int n, q, u, v, a[N];
vector <int> adj[N];
ll result;

/*
7 3
1 2
2 4
4 5
5 6
5 7
3 4
1 4
2 2 4
1 1
*/


int leafCnt, leaves[N], b[N];

void preDfs(int k, int p) {
    if (adj[k].size() == 1) {
        leaves[k] = 1;
    }
    else {
        leaves[k] = 0;
    }
    for (auto v : adj[k]) {
        if (v == p) {
            continue;
        }
        preDfs(v, k);
        leaves[k] += leaves[v];
    }
}

int par[N];

void dfs(int k, int p) {
    for (auto v : adj[k]) {
        if (v == p) {
            continue;
        }
        par[v] = k;
        dfs(v, k);
    }
}

vector <int> trace(int u) {
    vector <int> path;
    while (u) {
        path.push_back(u);
        u = par[u];
    }
    return path;
}

void updateTree(int u) {
    vector <int> path = trace(u);
    for (auto x : path) {
        b[x] ^= 1;
    }
}

int getSubtree(int u) {
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        ans += b[i];
    }
    return ans;
}

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

    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }

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

    for (int i = 1; i <= n; i++) {
        leafCnt += (adj[i].size() == 1);
    }
    preDfs(1, 1);
    for (int i = 1; i <= n; i++) {
        if (leaves[i] & 1) {
            b[i] = 1;
        }
        else {
            b[i] = 0;
        }
    }

    dfs(1, 1);

    while (q--) {
        int d;
        cin >> d;
        set <int> distinct;
        for (int i = 1; i <= d; i++) {
            cin >> a[i];
            if (adj[a[i]].size() == 1) {
                distinct.insert(a[i]);
            }
        }

        if ((leafCnt - distinct.size() + d) & 1) {
            cout << -1 << "\n";
            continue;
        }

        for (int i = 1; i <= d; i++) {
            updateTree(a[i]);
        }

        result = 0;
        ll odd = getSubtree(1) + d;
        ll even = n + d - odd;
        result = odd + 2 * even;
        if (b[1] == 1) {
            result--;
        }
        else {
            result -= 2;
        }
        cout << result << "\n";

        for (int i = 1; i <= d; i++) {
            updateTree(a[i]);
        }
    }

    return 0;
}

Compilation message (stderr)

cleaning.cpp: In function 'int main()':
cleaning.cpp:86:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:87:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   87 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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