Submission #951550

#	Time	Username	Problem	Language	Result	Execution time	Memory
951550		Nhoksocqt1	Fun Tour (APIO20_fun)	C++17	26 / 100	12 ms	8028 KiB

fun

#ifndef Nhoksocqt1
    #include "fun.h"
#endif // Nhoksocqt1
#include<bits/stdc++.h>
using namespace std;

#define inf 0x3f3f3f3f
#define sz(x) int((x).size())
#define fi first
#define se second
typedef long long ll;
typedef pair<int, int> ii;

template<class X, class Y>
	inline bool maximize(X &x, const Y &y) {return (x < y ? x = y, 1 : 0);}
template<class X, class Y>
	inline bool minimize(X &x, const Y &y) {return (x > y ? x = y, 1 : 0);}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int Random(int l, int r) {
    return uniform_int_distribution<int>(l, r)(rng);
}

const int MAXN = 100005;

#ifdef Nhoksocqt1

vector<int> adjp[MAXN];
int dist[5003][5003];

void bfs(int dist[], int y) {
    queue<int> qu;
    dist[y] = 1;
    qu.push(y);

    while(sz(qu)) {
        int x(qu.front()); qu.pop();

        for (int it = 0; it < sz(adjp[x]); ++it) {
            int y(adjp[x][it]);
            if(dist[y] == 0) {
                dist[y] = dist[x] + 1;
                qu.push(y);
            }
        }
    }
}

int hoursRequired(int x, int y) {
    return dist[x][y] - 1;
}

#endif // Nhoksocqt1

vector<int> adj[MAXN], B[2][MAXN];
int depth[MAXN], numNode, maxAsk;
bool dx[MAXN];

int askHoursRequired(int x, int y) {
    return hoursRequired(x, y);
}

ii dfsFar(int u, int p) {
    ii res = {0, u};
    for (int it = 0; it < sz(adj[u]); ++it) {
        int v(adj[u][it]);
        if(v != p && !dx[v]) {
            ii tmp = dfsFar(v, u); ++tmp.fi;
            res = max(res, tmp);
        }
    }

    return res;
}

vector<int> sub2(void) {
    for (int i = 0; i < numNode; ++i) {
        for (int j = i + 1; j < numNode; ++j) {
            if(askHoursRequired(i, j) == 1) {
                adj[i].push_back(j);
                adj[j].push_back(i);
            }
        }
    }

    vector<int> ans;
    int u = dfsFar(0, -1).se;
    ans.push_back(u);

    for (int i = 1; i < numNode; ++i) {
        int v = dfsFar(u, -1).se;
        dx[u] = 1;
        u = v;

        ans.push_back(v);
    }

    return ans;
}

bool check_sub3(void) {
    for (int i = 1; i < numNode; ++i) {
        if(askHoursRequired((i - 1) / 2, i) > 1)
            return false;
    }

    return true;
}

void dfs3(int u, vector<int> B[]) {
    B[depth[u]].push_back(u);
    for (int it = 0; it < sz(adj[u]); ++it) {
        int v(adj[u][it]);
        depth[v] = depth[u] + 1;
        dfs3(v, B);
    }
}

vector<int> sub3(void) {
    for (int i = 1; i < numNode; ++i)
        adj[(i - 1) / 2].push_back(i);

    depth[1] = depth[2] = 1;

    dfs3(1, B[0]);
    if(numNode > 2)
        dfs3(2, B[1]);

    vector<int> ans;
    int j(numNode);
    for (int i = numNode; i > 0; --i) {
        while(sz(B[0][i])) {
            int u(B[0][i].back());
            B[0][i].pop_back();

            while(j > 0 && !sz(B[1][j]))
                --j;

            ans.push_back(u);
            if(sz(B[1][j])) {
                int v(B[1][j].back());
                B[1][j].pop_back();
                ans.push_back(v);
            }
        }
    }

    ans.push_back(0);
    return ans;
}

vector<int> createFunTour(int _N, int _Q) {
    numNode = _N, maxAsk = _Q;

    if(numNode <= 500)
        return sub2();

    if(check_sub3())
        return sub3();
}

#ifdef Nhoksocqt1

int main(void) {
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    #define TASK "fun"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    int _N, _Q = 400000;
    cin >> _N >> _Q;

    for (int i = 0; i + 1 < _N; ++i) {
        int u, v;
        cin >> u >> v;
        adjp[u].push_back(v);
        adjp[v].push_back(u);
    }

    for (int i = 0; i < _N; ++i)
        bfs(dist[i], i);

    vector<int> funTour = createFunTour(_N, _Q);
    cout << "ANSWER: ";
    for (int it = 0; it < _N; ++it)
        cout << funTour[it] << ' '; cout << '\n';

    return 0;
}

#endif // Nhoksocqt1

Compilation message (stderr)

fun.cpp: In function 'std::vector<int> createFunTour(int, int)':
fun.cpp:160:1: warning: control reaches end of non-void function [-Wreturn-type]
  160 | }
      | ^

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 0 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 34