题目描述
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。
示例1
输入
[1,2,3,4,5,6,7],[3,2,4,1,6,5,7]
返回值
{1,2,5,3,4,6,7}
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| /**
* 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) {
if(pre.size() == 0)
{//如果为空，返回NULL
return NULL;
}
TreeNode* tempNode = new TreeNode(pre[0]);
int root = pre[0];
vector<int>leftPre;
vector<int>leftVin;
vector<int>rightPre;
vector<int>rightVin;
bool leftFlag = true;
int j = 1;
for(int i = 0;i<vin.size();i++)
{
if(root == vin[i])
{
leftFlag = false;
continue;
}
if(leftFlag)
{
leftPre.push_back(pre[j]);
leftVin.push_back(vin[i]);
j++;
}
else
{
rightPre.push_back(pre[j]);
rightVin.push_back(vin[i]);
j++;
}
}
tempNode->left = reConstructBinaryTree(leftPre,leftVin);
tempNode->right = reConstructBinaryTree(rightPre,rightVin);
return tempNode;
}
};
|