Given preorder and inorder traversal of a tree, construct the binary tree.
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基本功:
利用前序和中序构建二叉树
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code
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: ///help_buildTree_pi() template<typename Iteratorr> TreeNode *help_buildTree_pi(Iteratorr pre_first,Iteratorr pre_last, Iteratorr in_first,Iteratorr 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 = help_buildTree_pi(next(pre_first),next(pre_first,leftSize+1), in_first,next(in_first,leftSize)); root->right = help_buildTree_pi(next(pre_first,leftSize+1),pre_last,next(inRootPos),in_last); return root; } TreeNode* buildTree_pi(vector<int> &preorder,vector<int> &inorder){ return help_buildTree_pi(preorder.begin(),preorder.end(),inorder.begin(),inorder.end()); } };
时间: 2024-10-15 09:14:05