Submission #1024540

#	Time	Username	Problem	Language	Result	Execution time	Memory
1024540		stdfloat	Torrent (COI16_torrent)	C++17	31 / 100	2036 ms	20636 KiB

torrent

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

using ll = long long;

vector<bool> vis;

vector<int> pr;

vector<vector<int>> E;

void dfs_pr(int x, int p = -1) {
    pr[x] = p;
    for (auto i : E[x]) {
        if (i != p) dfs_pr(i, x);
    }
}

int dfs(int x) {
    vis[x] = true;

    vector<int> v;
    for (auto i : E[x]) {
        if (!vis[i]) v.push_back(dfs(i));
    }

    sort(v.rbegin(), v.rend());

    int mx = 0;
    for (int i = 0; i < (int)v.size(); i++) mx = max(mx, v[i] + i + 1);

    return mx;
}

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

    int n, a, b;
    cin >> n >> a >> b; a--; b--;

    E.assign(n, {});
    for (int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        
        E[--x].push_back(--y);
        E[y].push_back(x);
    }

    pr.assign(n, 0);
    dfs_pr(a);

    int cur = pr[b], mn = INT_MAX;
    while (cur != -1) {
        vis.assign(n, false);

        vis[cur] = true;
        int x = dfs(b);

        vis[cur] = false;

        mn = min(mn, max(x, dfs(a)));

        cur = pr[cur];
    }

    cout << mn;
}

• Subtask 1: 31 / 31
• Subtask 2: 0 / 69