minimum_height_trees

Author: hitzzc

README.md

@@ -226,6 +226,7 @@ Golang solution for leetcode. For each problem, there is a simple *_test.go to t
 #### [306. Additive Number](https://github.com/hitzzc/go-leetcode/tree/master/additive_number)
 #### [307. Range Sum Query - Mutable](https://github.com/hitzzc/go-leetcode/tree/master/range_sum_query_mutable)
 #### [309. Best Time to Buy and Sell Stock with Cooldown](https://github.com/hitzzc/go-leetcode/tree/master/best_time_to_buy_and_sell_stock_with_cooldown)
+#### [310. Minimum Height Trees](https://github.com/hitzzc/go-leetcode/tree/master/minimum_height_trees)
 
 
 

minimum_height_trees/minimum_height_trees.cpp

@@ -0,0 +1,27 @@
+class Solution {
+public:
+    vector<int> findMinHeightTrees(int n, vector<pair<int, int>>& edges) {
+        if (n <= 1) return {0};
+        vector<unordered_set<int>> graph(n);
+        for (auto& edge: edges) {
+        	graph[edge.first].insert(edge.second);
+        	graph[edge.second].insert(edge.first);
+        }
+        vector<int> current;
+        for (int i = 0; i < graph.size(); ++i) {
+        	if (graph[i].size() == 1) current.push_back(i);
+        }
+        while (true) {
+        	vector<int> next;
+        	for (auto& node: current) {
+        		for (auto& neighbor: graph[node]) {
+        			graph[neighbor].erase(node);
+        			if (graph[neighbor].size() == 1) next.push_back(neighbor);
+        		}
+        	}
+        	if (next.size() == 0) break;
+        	current.swap(next);
+        }
+        return current;
+    }
+};