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44 | class Solution {
public:
vector<int> findMinHeightTrees(int N, vector<vector<int>> &edges) {
if (N == 1)
return vector<int>({0});
queue<int> Q;
vector<vector<int>> G(N);
vector<int> inDegree(N);
for (auto &edge : edges) {
int u = edge[0];
int v = edge[1];
G[u].push_back(v);
G[v].push_back(u);
inDegree[u]++;
inDegree[v]++;
}
for (int i = 0; i < N; i++)
if (inDegree[i] == 1)
Q.push(i);
int size = N;
while (size > 2) {
int leafSize = Q.size();
size -= leafSize;
for (int i = 0; i < leafSize; i++) {
int cur = Q.front();
Q.pop();
for (int adj : G[cur]) {
inDegree[adj]--;
if (inDegree[adj] == 1)
Q.push(adj);
}
}
}
vector<int> ans;
while (!Q.empty()) {
ans.push_back(Q.front());
Q.pop();
}
return ans;
}
};
|