제출 #1271454

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1271454		red_souls	Spring cleaning (CEOI20_cleaning)	C++20	9 / 100	181 ms	18756 KiB

cleaning

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

const int N = 200000 + 16;
int n, q, u, v, a[N];
vector<int> adj[N];
ll result;

int leaves[N];

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

/* HLD */
int h[N], sz[N], par[N];
int chainId[N], chainArr[N], pos[N], chainHead[N], curPos = 1, curChain = 1, endPos[N];
int SZ; // số lượng vị trí hợp lệ sau HLD

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

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 to : adj[k]) {
        if (to == p) continue;
        if (heaviest == 0 || sz[to] > sz[heaviest]) heaviest = to;
    }
    if (heaviest) hld(heaviest, k);
    for (auto to : adj[k]) {
        if (to == p || to == heaviest) continue;
        curChain++;
        hld(to, k);
    }
    endPos[k] = curPos - 1;
}

int lca(int u, int v) {
    // So sánh bằng đầu chuỗi theo độ sâu head (KHÔNG dùng chainId trực tiếp)
    while (chainHead[chainId[u]] != chainHead[chainId[v]]) {
        if (h[chainHead[chainId[u]]] > h[chainHead[chainId[v]]]) {
            u = par[chainHead[chainId[u]]];
        } else {
            v = par[chainHead[chainId[v]]];
        }
    }
    return (h[u] < h[v]) ? u : 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) {
        if (l <= SZ && leaves[chainArr[l]] & 1) segmentTree[k].val = 1;
        else segmentTree[k].val = 0;
        segmentTree[k].lazy = 0;
        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];
    segmentTree[k].lazy = 0;
}

void down(int k, int l, int r) {
    if (!segmentTree[k].lazy) return;
    int mid = (l + r) >> 1;
    // flip left child
    segmentTree[k << 1].val = (mid - l + 1) - segmentTree[k << 1].val;
    segmentTree[k << 1].lazy ^= 1;
    // flip right child
    segmentTree[k << 1 | 1].val = (r - mid) - segmentTree[k << 1 | 1].val;
    segmentTree[k << 1 | 1].lazy ^= 1;
    segmentTree[k].lazy = 0;
}

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

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

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

node getSubtree(int u) {
    return getSeg(1, 1, SZ, pos[u], endPos[u]);
}

int leafCnt;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    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);
    }

    preDfs(1, 1);

    // chuẩn bị HLD
    h[1] = 0;
    par[1] = 1;
    dfs(1, 1);
    hld(1, 1);
    SZ = curPos - 1;          // số vị trí thực sự dùng (1..SZ)
    build(1, 1, SZ);

    for (int i = 1; i <= n; i++) if (adj[i].size() == 1) leafCnt++;

    while (q--) {
        int d; cin >> d;
        for (int i = 1; i <= d; i++) cin >> a[i];

        set<int> distinct;
        for (int i = 1; i <= d; i++) {
            updateTree(1, a[i]);            // toggle path 1..a[i]
            if (adj[a[i]].size() == 1) distinct.insert(a[i]);
        }

        if ((leafCnt - (int)distinct.size() + d) & 1) {
            result = -1;
        } else {
            ll oddAll = getSubtree(1).val + d;           // số node có odd (bao gồm n+i)
            ll evenSum = 2LL * (n + d - oddAll);
            result = oddAll + evenSum;                   // = 2*(n+d) - oddAll
            // chuyển về công thức đúng (loại node 1 khỏi tổng theo công thức gốc)
            if (getTree(1, 1).val == 1) result -= 1;
            else result -= 2;
        }
        cout << result << '\n';

        // rollback (toggle lại)
        for (int i = 1; i <= d; i++) updateTree(1, a[i]);
    }

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

cleaning.cpp: In function 'int main()':
cleaning.cpp:174:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  174 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:175:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  175 |         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: 0 / 17
• Subtask 7: 0 / 30