Submission #1283002

#	Time	Username	Problem	Language	Result	Execution time	Memory
1283002		daotuankhoi	Cats or Dogs (JOI18_catdog)	C++20	100 / 100	140 ms	25524 KiB

catdog

#include <bits/stdc++.h>

using namespace std;

#define ll long long


const int MAXN = 1e5 + 5;

vector<int> g[MAXN];

const int INF = 1e9;

int sz[MAXN], head[MAXN], heavy[MAXN], par[MAXN], in[MAXN], val[MAXN];

/// 0: cat, 1: dog

struct Node {
    int dp[2][2];
    Node() {
        dp[0][0] = dp[1][1] = 0;
        dp[0][1] = dp[1][0] = INF;
    }
};

Node comb(Node a, Node b) {
    Node res; res.dp[0][0] = res.dp[1][0] = res.dp[0][1] = res.dp[1][1] = INF;
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 2; j++) {
            if (a.dp[i][j] < INF) {
                for (int u = 0; u < 2; u++) {
                    for (int v = 0; v < 2; v++) {
                        if (b.dp[u][v] < INF) {
                            res.dp[i][v] = min(res.dp[i][v], a.dp[i][j] + b.dp[u][v] + (j ^ u));
                        }
                    }
                }
            }
        }
    }
    return res;
}

struct SegTree {
    vector<Node> tree;
    void init(int N) {
        tree.resize(N * 4);
    }
    void update(int id, int l, int r, int p, int cat, int dog) {
        if (p < l || r < p) return;
        if (l == r) {
            tree[id].dp[0][0] += cat;
            tree[id].dp[1][1] += dog;
            return;
        }
        int mid = (l + r) >> 1;
        update(id << 1, l, mid, p, cat, dog);
        update(id << 1 | 1, mid + 1, r, p, cat, dog);
        tree[id] = comb(tree[id << 1], tree[id << 1 | 1]);
    }
    pair<int, int> get(void) {
        Node ans = tree[1];
        int cat = min({ans.dp[0][0], ans.dp[0][1], ans.dp[1][0] + 1, ans.dp[1][1] + 1});
        int dog = min({ans.dp[1][0], ans.dp[1][1], ans.dp[0][0] + 1, ans.dp[0][1] + 1});
        return {cat, dog};
    }
} st[MAXN];

void dfs(int u, int p) {
    sz[u] = 1;
    for (int v : g[u]) {
        if (v != p) {
            par[v] = u;
            dfs(v, u);
            sz[u] += sz[v];
            if (heavy[u] == 0 || sz[v] > sz[heavy[u]]) heavy[u] = v;
        }
    }
}

void build(int u, int h) {
    head[u] = h;
    in[u] = ++sz[h];
    if (heavy[u]) build(heavy[u], h);
    for (int v : g[u]) {
        if (v != par[u] && v != heavy[u]) {
            build(v, v);
        }
    }
}

void initialize(int N, vector<int> A, vector<int> B) {
    for (int i = 0; i < N - 1; i++) {
        g[A[i]].emplace_back(B[i]);
        g[B[i]].emplace_back(A[i]);
    }
    dfs(1, 0);
    for (int i = 1; i <= N; i++) sz[i] = 0;
    build(1, 1);
    for (int i = 1; i <= N; i++) if (head[i] == i) {
        st[head[i]].init(sz[head[i]]);
    }
}


void upd(int u, int cat, int dog) {
    while (u) {
        auto lst = st[head[u]].get();
        st[head[u]].update(1, 1, sz[head[u]], in[u], cat, dog);
        auto cur = st[head[u]].get();
        cat = cur.first - lst.first;
        dog = cur.second - lst.second;
        u = par[head[u]];
    }
}

int cat(int v) {
    val[v] = 1;
    upd(v, 0, INF);
    Node res = st[1].tree[1];
    return min({res.dp[0][0], res.dp[0][1], res.dp[1][0], res.dp[1][1]});
}

int dog(int v) {
    val[v] = 2;
    upd(v, INF, 0);
    Node res = st[1].tree[1];
    return min({res.dp[0][0], res.dp[0][1], res.dp[1][0], res.dp[1][1]});
}

int neighbor(int v) {
    if (val[v] == 1) {
        upd(v, 0, -INF);
    } else {
        upd(v, -INF, 0);
    }
    val[v] = 0;
    Node res = st[1].tree[1];
    return min({res.dp[0][0], res.dp[0][1], res.dp[1][0], res.dp[1][1]});
}

• Subtask 1: 8 / 8
• Subtask 2: 30 / 30
• Subtask 3: 62 / 62