27 lines
687 B
JavaScript
27 lines
687 B
JavaScript
/**
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* Definition for a binary tree node.
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*/
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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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// 前序遍历：根左右
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// 中序遍历：左根右
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// 前序遍历知道根、中序遍历知道左边长度。
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/**
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* @param {number[]} preorder
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* @param {number[]} inorder
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* @return {TreeNode}
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*/
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export const buildTree = function (preorder, inorder) {
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if (inorder.length === 0) return null
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const root = new TreeNode(preorder[0])
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const index = inorder.indexOf(preorder[0])
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root.left = buildTree(preorder.slice(1, index + 1), inorder.slice(0, index))
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root.right = buildTree(preorder.slice(index + 1), inorder.slice(index + 1))
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return root
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}
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