C++实现重建二叉树

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

class Solution {
public:
    TreeNode* rebuild(vector<int>& pre, int pre_left, int pre_right, vector<int>& vin, int vin_left, int vin_right){
        if(pre_left > pre_right) return nullptr;
        
        TreeNode* root = new TreeNode(pre[pre_left]);
        
        int root_index = vin_left;
        
        while(root_index <= vin_right && vin[root_index++] != pre[pre_left]);
        --root_index;
        
        root->left = rebuild(pre, pre_left+1, root_index + pre_left - vin_left, vin, vin_left, root_index - 1);
        root->right = rebuild(pre, pre_left + root_index+1 - vin_left, pre_right, vin, root_index + 1, vin_right);
        return root;
    }
    
    TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> vin) {
        return rebuild(pre, 0, pre.size() - 1, vin, 0, vin.size() - 1);
    }
};

解析：