Submission #1225509

#	Time	Username	Problem	Language	Result	Execution time	Memory
1225509		minhpk	Unique Cities (JOI19_ho_t5)	C++20	64 / 100	178 ms	56572 KiB

joi2019_ho_t5

#include <bits/stdc++.h>
using namespace std;

int a, b;
vector<int> z[1000005];
int low[1000005], high[1000005], col[1000005], res[1000005];
vector<int> st;
int u = 0, v = 0, cur;
int best1_[1000005], best2_[1000005], best3_[1000005];

void dfs(int i, int par) {
    low[i] = 1;
    for (int p : z[i]) if (p != par) {
        high[p] = high[i] + 1;
        dfs(p, i);
        low[i] = max(low[i], low[p] + 1);
    }
}

void prepare_top3(int n) {
    for (int i = 1; i <= n; i++) {
        int v1 = 0, v2 = 0, v3 = 0, id1 = 0, id2 = 0, id3 = 0;
        for (int p : z[i]) {
            int L = low[p];
            if (L > v1) {
                v3 = v2; id3 = id2;
                v2 = v1; id2 = id1;
                v1 = L; id1 = p;
            } else if (L > v2) {
                v3 = v2; id3 = id2;
                v2 = L; id2 = p;
            } else if (L > v3) {
                v3 = L; id3 = p;
            }
        }
        best1_[i] = id1;
        best2_[i] = id2;
        best3_[i] = id3;
    }
}

void dfs1(int i, int par) {
    if (i != cur && z[i].size() == 1) {
        res[i] = max(res[i], (int)st.size());
        return;
    }
    int heavy = (best1_[i] != par ? best1_[i] : best2_[i]);
    int nextb = (best1_[i] != par ? best2_[i] : best3_[i]);
    if (nextb) {
        while (!st.empty() && high[i] - high[st.back()] <= low[nextb]) {
            st.pop_back();
        }
    }
    st.push_back(i);
    if (heavy) dfs1(heavy, i);
    if (heavy) {
        while (!st.empty() && high[i] - high[st.back()] <= low[heavy]) {
            st.pop_back();
        }
    }
    res[i] = max(res[i], (int)st.size());
    for (int p : z[i]) if (p != par && p != heavy) {
        while (!st.empty() && high[st.back()] >= high[i]) {
            st.pop_back();
        }
        st.push_back(i);
        dfs1(p, i);
    }
}

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

    cin >> a >> b;
    for (int i = 1; i < a; i++) {
        int x, y;
        cin >> x >> y;
        z[x].push_back(y);
        z[y].push_back(x);
    }
    for (int i = 1; i <= a; i++) {
        cin >> col[i];
    }

    dfs(1, 0);
    for (int i = 1; i <= a; i++)
        if (high[i] > high[u]) u = i;
    memset(high, 0, sizeof high);
    dfs(u, 0);
    for (int i = 1; i <= a; i++)
        if (high[i] > high[v]) v = i;

    cur = u;
    memset(high, 0, sizeof high);
    dfs(u, 0);
    prepare_top3(a);
    dfs1(u, 0);

    st.clear();
    cur = v;
    memset(high, 0, sizeof high);
    dfs(v, 0);
    prepare_top3(a);
    dfs1(v, 0);

    for (int i = 1; i <= a; i++) {
        if (b == 1)
            cout << (res[i] ? 1 : 0) << "\n";
        else
            cout << res[i] << "\n";
    }
    return 0;
}

• Subtask 1: 0 / 4
• Subtask 2: 32 / 32
• Subtask 3: 32 / 32
• Subtask 4: 0 / 32