-
Notifications
You must be signed in to change notification settings - Fork 0
/
T4.java
30 lines (27 loc) · 1.21 KB
/
T4.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
package com.cier.one;
/**
* 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。
*/
public class T4 {
public TreeNode reConstructBinaryTree(int[] pre, int[] in) {
TreeNode root = reConstructBinaryTree(pre, 0, pre.length - 1, in, 0, in.length - 1);
return root;
}
//前序遍历{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}
private TreeNode reConstructBinaryTree(int[] pre, int startPre, int endPre, int[] in, int startIn, int endIn) {
if (startPre > endPre || startIn > endIn) {
return null;
}
TreeNode root = new TreeNode(pre[startPre]);
for (int i = startIn; i <= endIn; i++) {
if (in[i] == pre[startPre]) {
root.left = reConstructBinaryTree(pre, startPre + 1, startPre + i - startIn, in, startIn, i - 1);
root.right = reConstructBinaryTree(pre, i - startIn + startPre + 1, endPre, in, i + 1, endIn);
}
}
return root;
}
}