Submission #894145

#	Time	Username	Problem	Language	Result	Execution time	Memory
894145		vovik	Cats or Dogs (JOI18_catdog)	C++17	100 / 100	100 ms	25452 KiB

catdog

#pragma GCC optimize(3)
#include <bits/stdc++.h>

void initialize(int N, std::vector<int> A, std::vector<int> B);

int cat(int v), dog(int v), neighbor(int v);

struct node {
    int a00, a01, a10, a11;
};

struct segTree {
    int n;
    std::vector<node> t;

    node merge(node a, node b) {
        node c;
        c.a00 = std::min(a.a00 + b.a00, a.a01 + b.a10);
        c.a01 = std::min(a.a00 + b.a01, a.a01 + b.a11);
        c.a10 = std::min(a.a10 + b.a00, a.a11 + b.a10);
        c.a11 = std::min(a.a10 + b.a01, a.a11 + b.a11);
        return c;
    }

    segTree() = default;

    segTree(int n) {
        while (__builtin_popcount(n) != 1) ++n;
        this->n = n, t = std::vector<node>(n * 2);
        for (auto&f: t) f.a01 = f.a10 = 1;
    }

    void modify(int i, int x, int y) {
        i += n, t[i].a00 += x, t[i].a01 += x, t[i].a10 += y, t[i].a11 += y;
        while (i /= 2) t[i] = merge(t[i * 2], t[i * 2 + 1]);
    }

    std::pair<int, int> get() {
        int x = std::min(t[1].a00, t[1].a01), y = std::min(t[1].a10, t[1].a11);
        return {std::min(x, y + 1), std::min(x + 1, y)};
    }
};

segTree ok[100005];

int pos[100005], p[100005], f[100005], sz[100005], len[100005], tp[100005];

std::vector<int> g[100005];

void cfs(int v = 1, int p = -1) {
    for (int i = 0; i < g[v].size(); ++i) if (g[v][i] == p) g[v].erase(g[v].begin() + i);
    sz[v] = 1;
    for (auto u: g[v]) if (u != p) cfs(u, v), sz[v] += sz[u], ::p[u] = v;
    std::sort(g[v].begin(), g[v].end(), [](const int&v, const int&u) { return sz[v] > sz[u]; });
}

void dfs(int v = 1, int s = 1) {
    f[v] = s, pos[v] = len[s]++;
    for (auto u: g[v]) dfs(u, u == g[v].front() ? s : u);
}

void initialize(int N, std::vector<int> A, std::vector<int> B) {
    for (int i = 0; i < A.size(); ++i) g[A[i]].push_back(B[i]), g[B[i]].push_back(A[i]);
    cfs(), dfs();
    for (int v = 1; v <= N; ++v) if (!pos[v]) ok[v] = len[v];
}

void modify(int v, int x, int y) {
    while (v) {
        auto [w0, w1] = ok[f[v]].get();
        ok[f[v]].modify(pos[v], x, y);
        auto [n0, n1] = ok[f[v]].get();
        x = n0 - w0, y = n1 - w1, v = p[f[v]];
    }
}

int query() {
    auto [a, b] = ok[1].get();
    return std::min(a, b);
}

int cat(int v) { return tp[v] = 1, modify(v, 1e9, 0), query(); }
int dog(int v) { return tp[v] = 2, modify(v, 0, 1e9), query(); }
int neighbor(int v) { return modify(v, -1e9 * (tp[v] == 1), -1e9 * (tp[v] == 2)), tp[v] = 0, query(); }

Compilation message (stderr)

catdog.cpp: In function 'void cfs(int, int)':
catdog.cpp:51:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   51 |     for (int i = 0; i < g[v].size(); ++i) if (g[v][i] == p) g[v].erase(g[v].begin() + i);
      |                     ~~^~~~~~~~~~~~~
catdog.cpp: In function 'void initialize(int, std::vector<int>, std::vector<int>)':
catdog.cpp:63:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |     for (int i = 0; i < A.size(); ++i) g[A[i]].push_back(B[i]), g[B[i]].push_back(A[i]);
      |                     ~~^~~~~~~~~~

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