2022-06-19

[Zheaoli]

2022-06-19

[dreamhunter2333]

package main

/*
 * @lc app=leetcode.cn id=508 lang=golang
 *
 * [508] 出现次数最多的子树元素和
 */
type TreeNode struct {
    Val   int
    Left  *TreeNode
    Right *TreeNode
}

// @lc code=start

func findFrequentTreeSum(root *TreeNode) []int {
    cache := make(map[int]int)
    res := make([]int, 0)

    var dfs func(node *TreeNode) int
    dfs = func(node *TreeNode) int {
        if node == nil {
            return 0
        }
        sumNode := node.Val + dfs(node.Left) + dfs(node.Right)
        cache[sumNode] += 1
        return sumNode
    }
    dfs(root)
    maxCount := 0
    for _, count := range cache {
        if count > maxCount {
            maxCount = count
        }
    }
    for sumNode, count := range cache {
        if count == maxCount {
            res = append(res, sumNode)
        }
    }
    return res
}

// @lc code=end

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[SaraadKun]

508. 出现次数最多的子树元素和

/**
 * Definition for a binary tree node.
 * 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;
 *     }
 * }
 */
class Solution {

    Map<Integer, Integer> map = new HashMap<>();
    int max = 0;

    public int[] findFrequentTreeSum(TreeNode root) {
        dfs(root);
        List<Integer> list = new ArrayList<>();
        for (Integer key : map.keySet()){
            if (map.get(key) == max) 
                list.add(key);
        }
        int[] res = new int[list.size()];
        int i = 0;
        for (Integer num : list) 
            res[i++] = num;
        return res;
    }

    int dfs(TreeNode root) {
        if (root == null) 
            return 0;
        int sum = dfs(root.left) + dfs(root.right) + root.val;
        map.put(sum, map.getOrDefault(sum, 0) + 1);
        max = Math.max(max, map.get(sum));
        return sum;
    }
}

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