package problems.medium;
import problems.utils.TreeNode;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Created by sherxon on 2/4/17.
*/
public class MostFrequentSubtreeSum {
static int[] findFrequentTreeSum(TreeNode root) {
if (root == null) return new int[0];
Map<Integer, Integer> fr = new HashMap<>();
sumNodes(root, fr);
List<Integer> list = new ArrayList<>();
int max = 0;
for (Integer integer : fr.keySet()) {
if (fr.get(integer) > max) {
list.clear();
max = fr.get(integer);
}
if (fr.get(integer) == max)
list.add(integer);
}
int[] a = new int[list.size()];
int i = 0;
for (Integer integer : list) {
a[i++] = integer;
}
return a;
}
static int sumNodes(TreeNode x, Map<Integer, Integer> fr) {
if (x == null) return 0;
x.val = sumNodes(x.left, fr) + sumNodes(x.right, fr) + x.val;
fr.put(x.val, fr.getOrDefault(x.val, 0) + 1);
return x.val;
}
}