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MostFrequentSubtreeSum.java
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MostFrequentSubtreeSum.java
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package com.dbc.code;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MostFrequentSubtreeSum {
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {
}
TreeNode(int val) {
this.val = val;
}
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
private List<Integer> res = new ArrayList<>();
private int dfs(TreeNode root, Map<Integer, Integer> map) {
if (root == null) return 0;
int leftNum = dfs(root.left, map);
int rightNum = dfs(root.right, map);
int total = leftNum + rightNum + root.val;
if (res.isEmpty() || map.getOrDefault(total, 0) + 1 == map.get(res.get(0))) res.add(total);
else if (map.getOrDefault(total, 0) + 1 > map.get(res.get(0))) {
res = new ArrayList<>();
res.add(total);
}
map.put(total, map.getOrDefault(total, 0) + 1);
return total;
}
public int[] findFrequentTreeSum(TreeNode root) {
Map<Integer, Integer> map = new HashMap<>();
dfs(root, map);
int[] ans = new int[res.size()];
for (int i = 0; i < res.size(); i++) ans[i] = res.get(i);
return ans;
}
}