Construct Binary Tree from Preorder and Inorder Traversal

最新推荐文章于 2024-01-17 14:50:43 发布

john_and_betty

最新推荐文章于 2024-01-17 14:50:43 发布

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分类专栏： leetcode

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class Solution {
public:
    TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
        if(inorder.size()==0)
            return NULL;
        return traverse(preorder,0,preorder.size()-1,inorder,0,inorder.size()-1);
    }
    TreeNode *traverse(vector<int>&preorder,int pbegin,int pend,vector<int>&inorder,int ibegin,int iend)
    {
        if(pbegin>pend)
           return NULL;
        TreeNode *root=new TreeNode(preorder[pbegin]);
        int index;
        for(int i=ibegin;i<=iend;i++)
        {
            if(root->val==inorder[i])
            {
                index=i;
                break;
            }
        }
        TreeNode *left=traverse(preorder,pbegin+1,pbegin+index-ibegin,inorder,ibegin,index-1);
        TreeNode *right=traverse(preorder,pbegin+index-ibegin+1,pend,inorder,index+1,iend);
        root->left=left;
        root->right=right;
        return root;
    }
};