Submission #1067887

#	Time	Username	Problem	Language	Result	Execution time	Memory
1067887		Plurm	Torrent (COI16_torrent)	C++11	69 / 100	100 ms	27740 KiB

torrent

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

vector<int> g[300005];
int dep[300005];
int chcnt[300005];
int col[300005];
int dp[300005];
int dfs(int u, int p = -1) {
    vector<int> vec;
    for (int v : g[u]) {
        if (v == p)
            continue;
        dfs(v, u);
        vec.push_back(dp[v]);
    }
    sort(vec.begin(), vec.end());
    reverse(vec.begin(), vec.end());
    for (int i = 0; i < vec.size(); i++) {
        dp[u] = max(dp[u], vec[i] + i + 1);
    }
    return dp[u];
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, a, b;
    cin >> n >> a >> b;
    if (a == b || n < 2)
        while (true)
            ;
    for (int i = 1; i < n; i++) {
        int x, y;
        cin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    memset(dep, 0x3f, sizeof(dep));
    dep[a] = dep[b] = 0;
    col[a] = 0;
    col[b] = 1;
    queue<int> q;
    q.push(a);
    q.push(b);
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        for (int v : g[u]) {
            if (dep[v] > dep[u] + 1) {
                dep[v] = dep[u] + 1;
                q.push(v);
                col[v] = col[u];
            }
        }
    }
    for (int i = 1; i <= n; i++) {
        for (int j : g[i]) {
            if (col[j] != col[i]) {
                g[i].erase(find(g[i].begin(), g[i].end(), j));
                break;
            }
        }
    }
    cout << max(dfs(a), dfs(b)) << endl;
    return 0;
}

Compilation message (stderr)

torrent.cpp: In function 'int dfs(int, int)':
torrent.cpp:19:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for (int i = 0; i < vec.size(); i++) {
      |                     ~~^~~~~~~~~~~~

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