508. Most Frequent Subtree Sum

public class Solution { int max = 1; public int[] findFrequentTreeSum(TreeNode root) { Map<Integer,Integer> map = new HashMap<>(); dfs(map,root); int maxi = 0; for(Integer i : map.keySet()) { if(map.get(i) > max) { max = map.get(i); maxi = i; } } if(max == 1) { int[] a = new int[map.size()]; int j = 0; for(Integer i: map.keySet()) { a[j++] = i; } return a; }else { List<Integer> list = new ArrayList<>(); for(Integer i: map.keySet()) { if(map.get(i) == max) { list.add(i); } } return list.stream().mapToInt(i->i).toArray(); } } public int dfs(Map<Integer,Integer> map, TreeNode root) { if(root == null) { return 0; } int sum = dfs(map, root.left) + dfs(map,root.right) + root.val; map.put(sum, map.getOrDefault(sum,0)+1); return sum; } }