Submission #1271516

#	Time	Username	Problem	Language	Result	Execution time	Memory
1271516		red_souls	Spring cleaning (CEOI20_cleaning)	C++20	26 / 100	205 ms	19220 KiB

cleaning

#include <bits/stdc++.h>
#define ll 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 leaves[N], leafCnt, 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 h[N], par[N], sz[N];
int chainHead[N], chainId[N], chainArr[N], pos[N], curPos = 1, curChain = 1, endPos[N];

void dfs(int k, int p) {
    sz[k] = 1;
    for (auto v : adj[k]) {
        if (v == p) {
            continue;
        }
        h[v] = h[k] + 1;
        par[v] = k;
        dfs(v, k);
        sz[k] += sz[v];
    }
}

void hld(int k, int p) {
    if (!chainHead[curChain]) {
        chainHead[curChain] = k;
    }
    chainId[k] = curChain;
    pos[k] = curPos;
    chainArr[curPos] = k;
    curPos++;
    int heaviest = 0;
    for (auto v : adj[k]) {
        if (v == p) {
            continue;
        }
        if (heaviest == 0 || sz[v] > sz[heaviest]) {
            heaviest = v;
        }
    }
    if (heaviest) {
        hld(heaviest, k);
    }
    for (auto v : adj[k]) {
        if (v == p || v == heaviest) {
            continue;
        }
        curChain++;
        hld(v, k);
    }
    endPos[k] = curPos - 1;
}

int lca(int u, int v) {
    while (chainId[u] != chainId[v]) {
        if (chainId[u] > chainId[v]) {
            u = par[chainHead[chainId[u]]];
        }
        else {
            v = par[chainHead[chainId[v]]];
        }
    }
    if (h[u] < h[v]) {
        return u;
    }
    return v;
}

struct node {
    int val = 0, lazy = 0;

    node operator + (const node &other) const {
        node ans;
        ans.val = val + other.val;
        return ans;
    }
};

node segmentTree[N << 2];

void build(int k, int l, int r) {
    if (l == r) {
        segmentTree[k].val = b[chainArr[l]];
        return;
    }
    int mid = l + r >> 1;
    build(k << 1, l, mid);
    build(k << 1 | 1, mid + 1, r);
    segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}

void down(int k, int l, int r) {
    if (segmentTree[k].lazy) {
        int mid = l + r >> 1;

        segmentTree[k << 1].val = (mid - l + 1) - segmentTree[k << 1].val;
        segmentTree[k << 1].lazy ^= 1;

        segmentTree[k << 1 | 1].val = (r - mid) - segmentTree[k << 1 | 1].val;
        segmentTree[k << 1 | 1].lazy ^= 1;

        segmentTree[k].lazy ^= 1;
    }
}

void update(int k, int l, int r, int x, int y) {
    if (l > y || x > r) {
        return;
    }
    if (l >= x && r <= y) {
        segmentTree[k].val = (r - l + 1) - segmentTree[k].val;
        segmentTree[k].lazy ^= 1;
        return;
    }
    int mid = l + r >> 1;
    down(k, l, r);
    update(k << 1, l, mid, x, y);
    update(k << 1 | 1, mid + 1, r, x, y);
    segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}

node get(int k, int l, int r, int x, int y) {
    if (l > y || x > r) {
        node ans;
        return ans;
    }
    if (l >= x && r <= y) {
        return segmentTree[k];
    }
    int mid = l + r >> 1;
    down(k, l, r);
    return get(k << 1, l, mid, x, y) + get(k << 1 | 1, mid + 1, r, x, y);
}

void updateTree(int u, int v) {
    int LCA = lca(u, v);
    while (chainId[u] != chainId[LCA]) {
        update(1, 1, curPos, pos[chainHead[chainId[u]]], pos[u]);
        u = par[chainHead[chainId[u]]];
    }
    while (chainId[v] != chainId[LCA]) {
        update(1, 1, curPos, pos[chainHead[chainId[v]]], pos[v]);
        v = par[chainHead[chainId[v]]];
    }
    if (h[u] < h[v]) {
        update(1, 1, curPos, pos[u], pos[v]);
    }
    else {
        update(1, 1, curPos, pos[v], pos[u]);
    }
}

node getTree(int u, int v) {
    node ans;
    int LCA = lca(u, v);
    while (chainId[u] != chainId[LCA]) {
        ans = get(1, 1, curPos, pos[chainHead[chainId[u]]], pos[u]) + ans;
        u = par[chainHead[chainId[u]]];
    }
    while (chainId[v] != chainId[LCA]) {
        ans = get(1, 1, curPos, pos[chainHead[chainId[v]]], pos[v]) + ans;
        v = par[chainHead[chainId[v]]];
    }
    if (h[u] < h[v]) {
        ans = get(1, 1, curPos, pos[u], pos[v]) + ans;
    }
    else {
        ans = get(1, 1, curPos, pos[v], pos[u]) + ans;
    }
    return ans;
}

node getSubtree(int k) {
    return get(1, 1, curPos, pos[k], endPos[k]);
}

int 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;
        }
    }

    dfs(1, 1);
    hld(1, 1);
    build(1, 1, curPos);

    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;
        }

        distinct.clear();
        vector <int> lst;
        for (int i = 1; i <= d; i++) {
            if (adj[a[i]].size() == 1) {
                auto it = distinct.lower_bound(a[i]);
                if (it != distinct.end()) {
                    lst.push_back(a[i]);
                }
                distinct.insert(a[i]);
            }
            else {
                lst.push_back(a[i]);
            }
        }

        for (auto x : lst) {
            updateTree(1, x);
        }

        result = 0;
        ll odd = getSubtree(1).val + d;
        ll even = n + d - odd;
        result += odd + 2 * even;

        if (getTree(1, 1).val == 1) {
            result--;
        }
        else {
            result -= 2;
        }

        cout << result << "\n";

        for (auto x : lst) {
            updateTree(1, x);
        }
    }

    return 0;
}

Compilation message (stderr)

cleaning.cpp: In function 'int main()':
cleaning.cpp:217:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  217 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:218:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  218 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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