Add 310_Minimum_Height_Trees.java

Author: Sean Prashad

Topological Sort/310_Minimum_Height_Trees.java

@@ -0,0 +1,42 @@
+class Solution {
+ public List<Integer> findMinHeightTrees(int n, int[][] edges) {
+ if (n == 1) {
+ return Arrays.asList(0);
+ }
+
+ List<Set<Integer>> adjList = new ArrayList<>();
+ List<Integer> leaves = new ArrayList<>();
+
+ for (int i = 0; i < n; i++) {
+ adjList.add(new HashSet<>());
+ }
+
+ for (int[] edge : edges) {
+ adjList.get(edge[0]).add(edge[1]);
+ adjList.get(edge[1]).add(edge[0]);
+ }
+
+ for (int i = 0; i < n; i++) {
+ if (adjList.get(i).size() == 1) {
+ leaves.add(i);
+ }
+ }
+
+ while (n > 2) {
+ n -= leaves.size();
+ List<Integer> newLeaves = new ArrayList<>();
+
+ for (int currLeaf : leaves) {
+ int adjLeaf = adjList.get(currLeaf).iterator().next();
+ adjList.get(adjLeaf).remove(currLeaf);
+ if (adjList.get(adjLeaf).size() == 1) {
+ newLeaves.add(adjLeaf);
+ }
+ }
+
+ leaves = newLeaves;
+ }
+
+ return leaves;
+ }
+}