Construct Binary Tree from Preorder and Inorder Traversal

描述

Given preorder and inorder traversal of a tree, construct the binary tree.

Note:You may assume that duplicates do not exist in the tree.

分析

无

代码

// Construct Binary Tree from Preorder and Inorder Traversal
// 递归，时间复杂度O(n)，空间复杂度O(\logn)
class Solution {
public:
    TreeNode* buildTree(vector& preorder, vector& inorder) {
        return buildTree(begin(preorder), end(preorder),
                begin(inorder), end(inorder));
    }
    template
    TreeNode* buildTree(InputIterator pre_first, InputIterator pre_last,
            InputIterator in_first, InputIterator in_last) {
        if (pre_first == pre_last) return nullptr;
        if (in_first == in_last) return nullptr;
        auto root = new TreeNode(*pre_first);
        auto inRootPos = find(in_first, in_last, *pre_first);
        auto leftSize = distance(in_first, inRootPos);
        root->left = buildTree(next(pre_first), next(pre_first,
                leftSize + 1), in_first, next(in_first, leftSize));
        root->right = buildTree(next(pre_first, leftSize + 1), pre_last,
                next(inRootPos), in_last);
        return root;
    }
};

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原文: https://soulmachine.gitbooks.io/algorithm-essentials/content/cpp/binary-tree/construction/construct-binary-tree-from-preorder-and-inorder-traversal.html