063_二叉树的直径

知识点：DFS、二叉树

LeetCode第五百四十三题：https://leetcode-cn.com/problems/diameter-of-binary-tree/solution/

语言：GoLang

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
var maxDistance int
func diameterOfBinaryTree(root *TreeNode) int {
    maxDistance = 0
    dfs(root)
    return maxDistance
}

// 获取树的深度
func dfs(root *TreeNode) int {
    if root == nil {
        return 0
    }

    leftMax := dfs(root.Left)
    rightMax := dfs(root.Right)

    maxDistance = max(leftMax + rightMax, maxDistance)
    return max(leftMax, rightMax) + 1
}

func max(a int, b int) int {
    if a > b {
        return a
    }
    return b
}