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。
/** * 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) {
int len = vin.size();
if(len == 0) return NULL;
vector<int> pre_left,pre_right, vin_left,vin_right;
TreeNode* node = new TreeNode(pre[0]);
int index = 0;
for(int i=0;i<len;++i)
{
if(vin[i]==pre[0])
{
index = i;
break;
}
}
for(int i=0;i<index;++i)
{
pre_left.push_back(pre[i+1]);
vin_left.push_back(vin[i]);
}
for(int i=0;i<len-index-1;++i)
{
pre_right.push_back(pre[index+1+i]);
vin_right.push_back(vin[index+1+i]);
}
node->left = reConstructBinaryTree(pre_left,vin_left);
node->right = reConstructBinaryTree(pre_right,vin_right);
return node;
}
};