C++解法

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> vin) {

            return Constructor(pre,0,pre.size(),vin,0,vin.size());
    }

    TreeNode* Constructor(vector<int>& pre,int pleft, int pright, vector<int>& vin, int vleft, int vright ){
            TreeNode* root = new TreeNode(pre[pleft]);

            if(pright-pleft==1 && vright-vleft == 1) {return root;}

            int root_index;
            for(int i=vleft;i<vright;i++){
                if(vin[i]==pre[pleft]) {root_index = i; break;}
            }

            int leftTreeNodesNum = root_index - vleft;
            if(leftTreeNodesNum>0) root->left = Constructor(pre,pleft+1,pleft+leftTreeNodesNum+1,vin,vleft,root_index);

            int rightTreeNodesNum = vright - root_index - 1;
            if(rightTreeNodesNum>0) root->right = Constructor(pre,pleft+leftTreeNodesNum+1,pright,vin,root_index+1,vright);

            return root;
    }
};