Submission #884421

#	Time	Username	Problem	Language	Result	Execution time	Memory
884421		chanhchuong123	Synchronization (JOI13_synchronization)	C++14	100 / 100	245 ms	24748 KiB

synchronization

#include <bits/stdc++.h>
using namespace std;
#define task ""
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()

const int MAX = 100010;
int n, m, q;
int timer;
int tin[MAX];
int bit[MAX];
int tout[MAX];
bool active[MAX];
int anc[17][MAX];
int a[MAX], c[MAX];
vector<int> adj[MAX];
pair<int, int> edges[MAX];

void update(int id, int delta) {
    for (; id <= n; id += id & -id)
        bit[id] += delta;
}

int get(int id) {
    int res = 0;
    for (; id > 0; id -= id & -id)
        res += bit[id];
    return  res;
}

void dfs(int u, int p) {
    if (p != -1) {
        for (int j = 1; j <= 16; ++j) anc[j][u] = anc[j - 1][anc[j - 1][u]];
    }
    tin[u] = ++timer;
    for (int v: adj[u]) if (v != p) {
        anc[0][v] = u;
        dfs(v, u);
    }
    tout[u] =  timer;
}

int root(int u) {
    int v = u;
    for (int j = 16; j >= 0; --j) if (anc[j][v] > 0) {
        if (get(tin[u]) == get(tin[anc[j][v]]))
            v = anc[j][v];
    }
    return v;
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(nullptr);

	if (fopen(task".inp", "r")) {
		freopen(task".inp", "r",  stdin);
		freopen(task".out", "w", stdout);
	}

    cin >> n >> m >> q;
    for (int i = 1; i <= n - 1; ++i) {
        int u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
        edges[i] = {u, v};
    }
    dfs(1, -1);
    for (int i = 1; i <= n; ++i) {
        a[i] = 1;
        update(tin[i], +1);
        update(tout[i] + 1, -1);
    }

    while (m--) {
        int j; cin >> j;
        int u, v; tie(u, v) = edges[j];
        if (anc[0][u] == v) swap(u, v);

        if (active[v]) {
            a[v] = c[v] = a[root(u)];
            update(tin[v], +1);
            update(tout[v] + 1, -1);
        } else {
            a[root(u)] += a[v] - c[v];
            update(tin[v], -1);
            update(tout[v] + 1, +1);
        }

        active[v] ^= 1;
    }

    while (q--) {
        int u; cin >> u;
        cout << a[root(u)] << '\n';
    }

	return 0;
}

Compilation message (stderr)

synchronization.cpp: In function 'int main()':
synchronization.cpp:56:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |   freopen(task".inp", "r",  stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
synchronization.cpp:57:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   57 |   freopen(task".out", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 10 / 10
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40