Submission #1097675

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097675		blackslex	Synchronization (JOI13_synchronization)	C++17	20 / 100	203 ms	24152 KiB

synchronization

#include<bits/stdc++.h>
#define lsb(x) (x &(-x))

using namespace std;
using pii = pair<int, int>;

const int N = 1e5 + 5, K = 19;
int n, m, q, x, y, t, tin[N], tout[N], par[N], dp[K][N], fwk[N], ans[N], lst[N];
vector<int> v[N];
bool f[N];

void upd (int idx, int val) {
    for (; idx < N; idx += lsb(idx)) fwk[idx] += val;
}

int qr (int idx) {
    int res = 0;
    for (; idx; idx -= lsb(idx)) res += fwk[idx];
    return res;
}

void dfs (int cur, int par) {
    tin[cur] = ++t; ::par[cur] = dp[0][cur] = par;
    for (auto &e: v[cur]) {
        if (par == e) continue;
        dfs(e, cur);
    }
    tout[cur] = t;
}

int lca (int a) {
    int res = a;
    for (int i = K - 1; i >= 0; i--) {
        if (dp[i][res] && qr(tin[dp[i][res]]) == qr(tin[a])) res = dp[i][res];
    }
    return res;
}

int main() {
    scanf("%d %d %d", &n, &m, &q);
    vector<pii> u(n - 1);
    for (auto &[x, y]: u) scanf("%d %d", &x, &y), v[x].emplace_back(y), v[y].emplace_back(x);
    dfs(1, 0);
    for (int i = 1; i < K; i++) {
        for (int j = 1; j <= n; j++) dp[i][j] = dp[i - 1][dp[i - 1][j]];
    }
    for (auto &[x, y]: u) if (::par[x] == y) swap(x, y);
    for (int i = 1; i <= n; i++) ans[i] = 1, upd(tin[i], -1), upd(tout[i], 1);
    while (m--) {
        scanf("%d", &x);
        auto [y, z] = u[--x];
        if (f[x]) {
            ans[z] = lst[z] = ans[lca(y)];
            upd(tin[z], -1); upd(tout[z], -1);
        } else {
            ans[lca(y)] += ans[z] - lst[z];
            upd(tin[z], 1); upd(tout[z], -1);
        }
        f[x] = !f[x];
    }
    while (q--) {
        scanf("%d", &x);
        printf("%d\n", ans[lca(x)]);
    }
}

Compilation message (stderr)

synchronization.cpp: In function 'int main()':
synchronization.cpp:40:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |     scanf("%d %d %d", &n, &m, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
synchronization.cpp:42:32: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |     for (auto &[x, y]: u) scanf("%d %d", &x, &y), v[x].emplace_back(y), v[y].emplace_back(x);
      |                           ~~~~~^~~~~~~~~~~~~~~~~
synchronization.cpp:50:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   50 |         scanf("%d", &x);
      |         ~~~~~^~~~~~~~~~
synchronization.cpp:62:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         scanf("%d", &x);
      |         ~~~~~^~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 10
• Subtask 4: 20 / 20
• Subtask 5: 0 / 40