重建二叉树

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    struct TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> in) {
        struct TreeNode *bt = (TreeNode*)malloc(sizeof(TreeNode));
        bt->val = pre[0];
        int index = 0;
        for (int i = 0; i < in.size(); i++){
            if (pre[0] == in[i]){
                index = i;
                break;
            }
        }
        vector<int> inL;
		for (int i = 0; i < index; i++)
			inL.push_back(in[i]);
        vector<int> inR;
        for (int i = index+1; i < pre.size(); i++)
			inR.push_back(in[i]);
        vector<int> preL;
		for (int i = 1; i <= inL.size(); i++)
			preL.push_back(pre[i]);
        vector<int> preR;
		for (int i = inL.size()+1; i < pre.size(); i++)
			preR.push_back(pre[i]);

    	if(index==0)
            bt->left = NULL;
        else
            bt->left = reConstructBinaryTree(preL, inL);

        if(preR.size() == 0)
            bt->right = NULL;
        else
            bt->right = reConstructBinaryTree(preR, inR);
        return bt;
    }
};