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c_cpp
2 years ago
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// https://www.codingninjas.com/codestudio/library/find-the-roots-of-a-tree-that-gives-minimum-height

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;

    vector<int> degree(n, 0);
    vector<vector<int>> neighborVertex(n);

    for (int i = 0; i < n - 1; ++ i) {
        int x, y;
        cin >> x >> y;
        degree[x] ++;
        degree[y] ++;

        neighborVertex[x].push_back(y);
        neighborVertex[y].push_back(x);
    }

    queue<int> q;

    for (int idx = 0; idx < n; ++ idx) {
        if (degree[idx] == 1) {
            q.push(idx);
        }
    }

    int temp = n;
    while (temp > 2) {
        temp = temp - q.size();

        int tmp = q.size();
        for (int i = 0; i < tmp; ++ i) {
            int root = q.front();
            q.pop();

            for (int j = 0; j < neighborVertex[root].size(); ++j) {
                degree[neighborVertex[root][j]] --;
                if (degree[neighborVertex[root][j]] == 1) {
                    q.push(neighborVertex[root][j]);
                }
            }
        }
    }

    vector<int> res;
    while (!q.empty()) {
        res.push_back(q.front());
        q.pop();
    }

    sort(res.begin(), res.end());
    for (auto i: res) {
        cout << i << " ";
    }
    return 0;
}
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