Submission #1106267

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106267		CodeLakVN	Railway (BOI17_railway)	C++17	100 / 100	89 ms	29548 KiB

railway

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define name "main"
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FOD(i, b, a) for (int i = (b); i >= (a); i--)

template <class U, class V>
    bool maximize(U &x, V y) {
        if (x < y) { x = y; return true; }
        return false;
    }

template <class U, class V>
    bool minimize(U &x, V y) {
        if (x > y) { x = y; return true; }
        return false;
    }

const int INF = 1e9;
const int N = 1e5 + 5;

int numNode, numQuery, limit;
vector<pair<int, int>> adj[N];
vector<int> query[N];
int in[N];
int cur = 0;

struct LCA {
    int par[20][N], high[N];

    void dfs(int u) {
        in[u] = ++cur;
        for (pair<int, int> e : adj[u]) {
            int v, id;
            tie(v, id) = e;
            if (v == par[0][u]) continue;
            par[0][v] = u;
            high[v] = high[u] + 1;
            dfs(v);
        }
    }

    void setup() {
        dfs(1);
        FOR(i, 1, 18) FOR(u, 1, numNode)
            par[i][u] = par[i - 1][par[i - 1][u]];
        high[0] = -1;
    }

    int getLCA(int u, int v) {
        if (high[u] < high[v]) swap(u, v);
        FOD(i, 18, 0) if (high[par[i][u]] >= high[v])
            u = par[i][u];
        if (u == v) return u;
        FOD(i, 18, 0) if (par[i][u] != par[i][v]) {
            u = par[i][u];
            v = par[i][v];
        }
        return par[0][u];
    }
} lca;

bool cmp(int x, int y) {
    return in[x] < in[y];
}

int cnt[N], ans[N];

void dfs(int u, int p) {
    for (pair<int, int> e : adj[u]) {
        int v, id;
        tie(v, id) = e;
        if (v == p) continue;
        dfs(v, u);
        cnt[u] += cnt[v];
        ans[id] = cnt[v];
    }
}

int main() {
    ios_base::sync_with_stdio(NULL);
    cin.tie(0); cout.tie(0);
    if (fopen(name".inp", "r")) {
        freopen(name".inp", "r", stdin);
        freopen(name".out", "w", stdout);
    }

    cin >> numNode >> numQuery >> limit;
    FOR(i, 1, numNode - 1) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    FOR(i, 1, numQuery) {
        int s;
        cin >> s;
        while (s--) {
            int u;
            cin >> u;
            query[i].push_back(u);
        }
    }

    lca.setup();
    FOR(i, 1, numQuery)  {
        vector<int> nodes;
        FOR(j, 0, query[i].size() - 1) {
            nodes.push_back(query[i][j]);
            if (j > 0) nodes.push_back(lca.getLCA(query[i][j - 1], query[i][j]));
        }
        sort(nodes.begin(), nodes.end(), cmp);
        nodes.erase(unique(nodes.begin(), nodes.end()), nodes.end());
        nodes.push_back(nodes[0]);

        FOR(j, 1, nodes.size() - 1) {
            int p = lca.getLCA(nodes[j], nodes[j - 1]);
            cnt[nodes[j]]++, cnt[nodes[j - 1]]++;
            cnt[p] -= 2;
        }
    }

    dfs(1, -1);
    int res = 0;
    vector<int> trace;
    FOR(i, 1, numNode - 1) if (ans[i] / 2 >= limit) res++, trace.push_back(i);

    cout << res << "\n";
    for (int i : trace) cout << i << " ";

    return 0;
}

// Lak lu theo dieu nhac ^.^

Compilation message (stderr)

railway.cpp: In function 'int main()':
railway.cpp:8:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 | #define FOR(i, a, b) for (int i = (a); i <= (b); i++)
      |                                          ^
railway.cpp:112:9: note: in expansion of macro 'FOR'
  112 |         FOR(j, 0, query[i].size() - 1) {
      |         ^~~
railway.cpp:8:42: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 | #define FOR(i, a, b) for (int i = (a); i <= (b); i++)
      |                                          ^
railway.cpp:120:9: note: in expansion of macro 'FOR'
  120 |         FOR(j, 1, nodes.size() - 1) {
      |         ^~~
railway.cpp:88:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
railway.cpp:89:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |         freopen(name".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25