重建二叉树_牛客题霸_牛客网

 TreeNode* reConstructBinaryTree(vector<int>& preOrder, vector<int>& vinOrder) {
        // write code here
        int n = preOrder.size();
        int m = vinOrder.size();
        if(n == 0 || m == 0)  return NULL;
        TreeNode* root = new TreeNode(preOrder[0]);
        for(int i=0; i<vinOrder.size(); i++)
        {
            if(preOrder[0] == vinOrder[i])
            {
                vector<int>leftpre(preOrder.begin()+1, preOrder.begin()+i+1);
                vector<int>leftvin(vinOrder.begin(),  vinOrder.begin() + i);
                root->left = reConstructBinaryTree(leftpre, leftvin);
                vector<int>rightpre(preOrder.begin()+i+1, preOrder.end());
                vector<int>rightvin(vinOrder.begin() +i+1, vinOrder.end());
                root->right = reConstructBinaryTree(rightpre, rightvin);
                break;
            }
        }
        return root;
    }