題目描述
輸入某二叉樹的前序遍歷和中序遍歷的結(jié)果，請(qǐng)重建出該二叉樹冤灾。假設(shè)輸入的前序遍歷和中序遍歷的結(jié)果中都不含重復(fù)的數(shù)字前域。例如輸入前序遍歷序列{1,2,4,7,3,5,6,8}和中序遍歷序列{4,7,2,1,5,3,8,6}，則重建二叉樹并返回韵吨。
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
import java.util.*;
public class Solution {
public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
if(pre.length == 0 || in.length == 0) {
return null;
}
TreeNode root = new TreeNode(pre[0]);
for(int i = 0; i<in.length;i++) {
if(in[i] == pre[0]) {
// 遞歸獲取左節(jié)點(diǎn)
root.left = reConstructBinaryTree(
Arrays.copyOfRange(pre, 1, i+1),
Arrays.copyOfRange(in, 0, i));
// 遞歸獲取右節(jié)點(diǎn)
root.right = reConstructBinaryTree(
Arrays.copyOfRange(pre, i+1, pre.length),
Arrays.copyOfRange(in, i+1, in.length));
}
}
return root;
}
}
