Submission #723543

#	Time	Username	Problem	Language	Result	Execution time	Memory
723543		t6twotwo	Village (BOI20_village)	C++17	100 / 100	100 ms	23796 KiB

Village

#include <bits/stdc++.h>
using namespace std;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    vector<vector<int>> adj(n);
    for (int i = 1; i < n; i++) {
        int x; cin >> x; x--;
        int y; cin >> y; y--;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    vector<int> amin(n), amax(n);
    iota(amin.begin(), amin.end(), 0);
    int ansmin = 0;
    int64_t ansmax = 0;
    auto dfs = [&](auto dfs, int x, int p) -> bool {
        vector<int> b;
        for (int y : adj[x]) {
            if (y != p) {
                if (dfs(dfs, y, x)) {
                    b.push_back(y);
                }
            }
        }
        if (b.empty()) {
            return 1;
        }
        ansmin += b.size() * 2;
        if (b.size() % 2 == 1) {
            swap(amin[x], amin[b[0]]);
            for (int i = 1; i < b.size(); i += 2) {
                swap(amin[b[i]], amin[b[i + 1]]);
            }
        } else {
            swap(amin[x], amin[b[0]]);
            swap(amin[x], amin[b[1]]);
            for (int i = 2; i < b.size(); i += 2) {
                swap(amin[b[i]], amin[b[i + 1]]);
            }
        }
        return 0;
    };
    if (dfs(dfs, 0, -1)) {
        swap(amin[0], amin[adj[0][0]]);
        ansmin += 2;
    }
    vector<int> sz(n);
    auto init = [&](auto init, int x, int p) -> void {
        sz[x] = 1;
        for (int y : adj[x]) {
            if (y != p) {
                init(init, y, x);
                sz[x] += sz[y];
            }
        }
        ansmax += 2 * min(sz[x], n - sz[x]);
    };
    auto find = [&](auto find, int x, int p) -> int {
        for (int y : adj[x]) {
            if (y != p && sz[y] * 2 > n) {
                return find(find, y, x);
            }
        }
        return x;
    };
    init(init, 0, -1);
    int c = find(find, 0, -1);
    vector<int> b;
    auto dfs2 = [&](auto dfs2, int x, int p) -> void {
        b.push_back(x);
        for (int y : adj[x]) {
            if (y != p) {
                dfs2(dfs2, y, x);
            }
        }
    };
    dfs2(dfs2, 0, -1);
    for (int i = 0; i < n; i++) {
        amax[b[i]] = b[(i + n / 2) % n];
    }
    cout << ansmin << " " << ansmax << "\n";
    for (int i = 0; i < n; i++) {
        cout << amin[i] + 1 << " \n"[i == n - 1];
    }
    for (int i = 0; i < n; i++) {
        cout << amax[i] + 1 << " \n"[i == n - 1];
    }
    return 6/22;
}

Compilation message (stderr)

Village.cpp: In lambda function:
Village.cpp:34:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |             for (int i = 1; i < b.size(); i += 2) {
      |                             ~~^~~~~~~~~~
Village.cpp:40:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |             for (int i = 2; i < b.size(); i += 2) {
      |                             ~~^~~~~~~~~~
Village.cpp: In function 'int main()':
Village.cpp:70:9: warning: unused variable 'c' [-Wunused-variable]
   70 |     int c = find(find, 0, -1);
      |         ^
Village.cpp: In instantiation of 'main()::<lambda(auto:23, int, int)> [with auto:23 = main()::<lambda(auto:23, int, int)>]':
Village.cpp:46:23:   required from here
Village.cpp:34:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   34 |             for (int i = 1; i < b.size(); i += 2) {
      |                             ~~^~~~~~~~~~
Village.cpp:40:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |             for (int i = 2; i < b.size(); i += 2) {
      |                             ~~^~~~~~~~~~

• Subtask 1: 12 / 12
• Subtask 2: 38 / 38
• Subtask 3: 50 / 50