Submission #733143

#	Time	Username	Problem	Language	Result	Execution time	Memory
733143		nguyentunglam	Inside information (BOI21_servers)	C++17	5 / 100	3533 ms	34744 KiB

servers

#include<bits/stdc++.h>
#define fi first
#define se second
#define endl "\n"
#define ii pair<int, int>
using namespace std;
const int N = 2e5 + 10;
bool dd[N];
int sz[N], ans[N];
vector<pair<int, int>> adj[N], query1[N];
vector<int> query2[N];
int n, k, cnt[N], type[N];


int calc(int u, int par) {
    sz[u] = 1;
    for(auto &[v, w] : adj[u]) if (!dd[v] && v != par) {
        sz[u] += calc(v, u);
    }
    return sz[u];
}

int getcentr(int u, int par, int cnt) {
    for(auto &[v, w] : adj[u]) if (!dd[v] && v != par && sz[v] > 2 * cnt)
        return getcentr(v, u, cnt);
    return u;
}
int bit[N << 1];

void up(int pos, int val) {
    while (pos <= k) {
        bit[pos] += val;
        pos += pos & -pos;
    }
}

int get(int pos) {
    int ret = 0;
    while (pos) {
        ret += bit[pos];
        pos -= pos & -pos;
    }
    return ret;
}

void dfs1(int u, int pre) {
    up(pre, 1);
    cnt[u] = pre;
    for(auto &[v, w] : adj[u]) if (!dd[v] && w > pre) {
        dfs1(v, w);
    }
}

void dfs2(int u, int pre) {
    for(int &idx : query2[u]) {
        ans[idx] += get(idx);
    }
    for(auto &[a, idx] : query1[u]) {
        ans[idx] |= (cnt[a] > 0 && cnt[a] < idx);
    }

    for(auto &[v, w] : adj[u]) if (!dd[v] && w < pre) {
        dfs2(v, w);
    }
}

void dfs3(int u, int pre) {
    up(pre, -1);
    cnt[u] = 0;
    for(auto &[v, w] : adj[u]) if (!dd[v] && w > pre) {
        dfs3(v, w);
    }
}

void centroid(int u) {
    int node = getcentr(u, u, calc(u, u));
    dd[node] = 1;
//    cout << node << endl;
    vector<pair<int, int> > lst;
    for(auto &[v, w] : adj[node]) if (!dd[v]) lst.emplace_back(-w, v);
    sort(lst.begin(), lst.end());
    for(auto &[w, v] : lst) {
        w = -w;
        cnt[node] = w;
        up(w, 1);
        dfs2(v, w);
        up(w, -1);
        cnt[node] = 0;
        dfs1(v, w);
    }
    for(int &idx : query2[node]) {
        ans[idx] += get(idx);
    }
    for(auto &[a, idx] : query1[node]) {
        ans[idx] |= (cnt[a] > 0 && cnt[a] < idx);
    }
    for(auto &[w, v] : lst) {
        dfs3(v, w);
    }
    for(auto &[v, w] : adj[node]) if (!dd[v]) centroid(v);
}

int main() {
    #define task ""
    cin.tie(0) -> sync_with_stdio(0);
    if (fopen ("task.inp", "r")) {
        freopen ("task.inp", "r", stdin);
        freopen ("task.out", "w", stdout);
    }
    if (fopen (task".inp", "r")) {
        freopen (task".inp", "r", stdin);
        freopen (task".out", "w", stdout);
    }
    cin >> n >> k;
    k = n + k - 1;
    for(int i = 1; i <= k; i++) {
        char c; cin >> c;
        if (c == 'S') {
            int a, b; cin >> a >> b;
            adj[a].emplace_back(b, i);
            adj[b].emplace_back(a, i);
        }
        if (c == 'Q') {
            int a, d; cin >> a >> d;
            if (a == d) ans[i] = 1;
            query1[d].emplace_back(a, i);
            type[i] = 1;
        }
        if (c == 'C') {
            int d; cin >> d;
            query2[d].push_back(i);
            type[i] = 2;
            ans[i] = 1;
        }
    }
    centroid(1);
    for(int i = 1; i <= k; i++) {
        if (type[i] == 1) cout << (ans[i] ? "yes\n" : "no\n");
        else if (type[i] == 2) cout << ans[i] << endl;
    }

}

Compilation message (stderr)

servers.cpp: In function 'int main()':
servers.cpp:107:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |         freopen ("task.inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
servers.cpp:108:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         freopen ("task.out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
servers.cpp:111:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
servers.cpp:112:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 2.5 / 2.5
• Subtask 2: 2.5 / 2.5
• Subtask 3: 0 / 2.5
• Subtask 4: 0 / 2.5
• Subtask 5: 0 / 5
• Subtask 6: 0 / 5
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 12.5
• Subtask 10: 0 / 12.5
• Subtask 11: 0 / 17.5
• Subtask 12: 0 / 17.5