lintcode二叉查找树中搜索区间 java

给定两个值 k1 和 k2（k1 < k2）和一个二叉查找树的根节点。找到树中所有值在 k1 到 k2 范围内的节点。即打印所有x (k1 <= x <= k2) 其中 x 是二叉查找树的中的节点值。返回所有升序的节点值。

样例

如果有 k1 = 

10

 和 k2 = 

22

,
你的程序应该返回 

[12, 20, 22]

.

20
/  \
8   22
/ \
4   12

/**
* Definition of TreeNode:
* public class TreeNode {
*     public int val;
*     public TreeNode left, right;
*     public TreeNode(int val) {
*         this.val = val;
*         this.left = this.right = null;
*     }
* }
*/

public class Solution {
/*
* @param root: param root: The root of the binary search tree
* @param k1: An integer
* @param k2: An integer
* @return: return: Return all keys that k1<=key<=k2 in ascending order
*/
public List<Integer> searchRange(TreeNode root, int k1, int k2) {
if(root == null){
return null;
}
List<Integer> list = new ArrayList<Integer>();
if(root.val <=k2 && root.val >= k1){
List<Integer> retLeft = searchRange(root.left, k1, k2);
if(null != retLeft){
list.addAll(retLeft);
}
list.add(root.val);
List<Integer> retRight = searchRange(root.right, k1, k2);
if(null != retRight){
list.addAll(retRight);
}
}else if(root.val > k2){
List<Integer> retLeft = searchRange(root.left, k1, k2);
if(null != retLeft){
list.addAll(retLeft);
}
}else if(root.val < k1){
List<Integer> re
a495
tRight = searchRange(root.right, k1, k2);
if(null != retRight){
list.addAll(retRight);
}
}
return list;
}
}