37 lines
865 B
JavaScript
37 lines
865 B
JavaScript
/*
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* @lc app=leetcode id=543 lang=javascript
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*
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* [543] Diameter of Binary Tree
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*/
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/**
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* Definition for a binary tree node.
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* function TreeNode(val) {
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* this.val = val;
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* this.left = this.right = null;
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* }
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*/
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function maxDepth(root, res) {
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if (root === null) return 0;
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const l = maxDepth(root.left, res);
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const r = maxDepth(root.right, res);
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res.val = Math.max(res.val, l + r);
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return 1 + Math.max(l, r);
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}
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/**
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* @param {TreeNode} root
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* @return {number}
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*/
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var diameterOfBinaryTree = function(root) {
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// 如果不计算max， 直接1+ Math.max(maxLeft, maxRight)， 得到的结果实际上是经过root节点的最大值，并不一定是总体最大值
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// 题目也做了说明， ”最大值不一定经过root“
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if (root === null) return 0;
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const res = {
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val: 0
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};
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maxDepth(root, res);
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return res.val;
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};
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