leetcode 508 && 可以将 数组 转化为二叉树

package com.javamvc.learning.leetcode;

import java.util.HashMap;
import java.util.Map;

public class leetCode508 {

static class TreeNode {
	TreeNode left;
	TreeNode right;
	int val;

	TreeNode(int val) {
		this.val = val;
	}

	public static void main(String[] args) {
		Integer[] arr = new Integer[] { 5, 2, -3, 5, -6, 5 };
		TreeNode root = createBinaryTreeByArray(arr, 0);
		Solution solution = new Solution();
		int[] findFrequentTreeSum = solution.findFrequentTreeSum(root);
		for (int i : findFrequentTreeSum) {
			System.out.println(i);
		}

	}

	static TreeNode createBinaryTreeByArray(Integer[] array, int index) {
		TreeNode tn = null;
		if (index < array.length) {
			Integer value = array[index];
			if (value == null) {
				return null;
			}
			tn = new TreeNode(value);
			tn.left = createBinaryTreeByArray(array, 2 * index + 1);
			tn.right = createBinaryTreeByArray(array, 2 * index + 2);
			return tn;
		}
		return tn;
	}

	static class Solution {
		private Map<Integer, Integer> map = new HashMap<>();
		private int degree = 0; // the highest frequency of the sum
		private int size = 0; // to determine the number of most frequent sum

		public int[] findFrequentTreeSum(TreeNode root) {
			findSum(root); // post order traversal
			int[] res = new int[size];
			int i = 0;
			// putting all the element into the final array
			for (int n : map.keySet()) {
				if (map.get(n) == degree) {
					res[i++] = n;
				}
			}
			return res;
		}

		public int findSum(TreeNode node) {
			// when node == null, the sum = 0
			if (node == null) {
				return 0;
			}
			int left = findSum(node.left); // find the sum of the left subtree
			int right = findSum(node.right); // find the sum of the right subtree
			int sum = left + right + node.val; // find the sum of the tree rooted by node
			map.put(sum, map.getOrDefault(sum, 0) + 1);
			System.out.println(map.size());
			System.out.println(map.values());
			for (int m = 0; m < map.size(); m++) {
				System.out.println(map.keySet() + "\t23569569");
			}
			if (map.get(sum) > degree) {
				degree = map.get(sum); // update the highest frequency
				size = 1; // the number of sum with this frequency is reset back to 1
			} else if (map.get(sum) == degree) {
				size++; // increase the number of the most frequent sum
			}
			return sum;
		}
	}

}}