Submission #877720

#	Time	Username	Problem	Language	Result	Execution time	Memory
877720		hafo	Synchronization (JOI13_synchronization)	C++14	100 / 100	326 ms	37008 KiB

synchronization

#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define Size(x) (int) x.size()
#define all(x) x.begin(), x.end()
using namespace std;

template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}

const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 2e5 + 7;
const ll oo = 1e18 + 69;

int n, m, q, u, v, x, st[maxn], en[maxn], timer = 0, cnt[maxn], last[maxn];
vector<int> g[maxn];
pa ed[maxn];
bool active[maxn];

struct BIT {
    int bit[maxn];

    void update(int x, int val) {
        for(; x <= n; x += x&-x) bit[x] += val;
    }
    
    int get(int x) {
        int ans = 0;
        for(; x; x -= x&-x) ans += bit[x];
        return ans;
    }

} bit;

struct LCA {
    int p[LOG][maxn], dep[maxn];

    void dfs(int u, int par) {
        p[0][u] = par;
        for(auto v:g[u]) {
            if(v == par) continue;
            dep[v] = dep[u] + 1;
            dfs(v, u);
        }
    }

    void init() {
        dep[1] = 0;
        dfs(1, 0);
        for(int i = 1; i < LOG; i++) {
            for(int u = 1; u <= n; u++) p[i][u] = p[i - 1][p[i - 1][u]];
        }
    }

    int find_nxt(int u) {
        for(int i = LOG - 1; i >= 0; i--) {
            if(p[i][u] == 0) continue;
            if(bit.get(st[p[i][u]]) == bit.get(st[u])) u = p[i][u];
        }
        return u;
    }

} lca;

void dfs(int u, int par) {
    st[u] = ++timer;
    for(auto v:g[u]) {
        if(v == par) continue;
        dfs(v, u);
    }
    en[u] = timer;
}

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

    //freopen(TASK".inp", "r", stdin);
    //freopen(TASK".out", "w", stdout);

    cin>>n>>m>>q;
    for(int i = 1; i < n; i++) {
        cin>>ed[i].fi>>ed[i].se;
        g[ed[i].fi].pb(ed[i].se);
        g[ed[i].se].pb(ed[i].fi);
    }

    dfs(1, 0);
    lca.init();

    for(int i = 1; i <= n; i++) {
        cnt[i] = 1;
        bit.update(st[i], -1);
        bit.update(en[i] + 1, 1);
    }
    
    while(m--) {
        cin>>x;
        u = ed[x].fi, v = ed[x].se;
        if(st[u] > st[v]) swap(u, v);
        if(active[x]) {
            cnt[v] = last[v] = cnt[lca.find_nxt(u)];
            bit.update(st[v], -1);
            bit.update(en[v] + 1, 1);
        } else {
            bit.update(st[v], 1);
            bit.update(en[v] + 1, -1);
            cnt[lca.find_nxt(u)] += cnt[v] - last[v];
        }
        active[x] ^= 1;
    }

    while(q--) {
        cin>>x;
        cout<<cnt[lca.find_nxt(x)]<<"\n";
    }
    return 0;
}

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