How does LeetCode find all the elements in two binary search trees
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One, two binary search trees for all the elements
1. Brief introduction of the problem.
Here are two binary search trees, root1 and root2.
Please return a list of all the integers in the "two trees" and sort them in ascending order.
2, example description
Input: root1 = [2jue 1pr 4], root2 = [1je 0pr 3]
Output: [0meme 1 pyrrine 1 pyrrine 2pime 3 pyrrine 4]
Example 2:
Input: root1 = [0jimi 10jue 10], root2 = [5meme 1je 7je 0je 2]
Output: [- 10pc0re0p0pl 1pyrrine 25pyrm 7pc10]
Example 3:
Input: root1 = [], root2 = [5Jing 1Jing 7JI 0jue 2]
Output: [0pyrrine 1 pyrrine 2pyrrine 5pr 7]
Example 4:
Input: root1 = [0mai Mei 10j 10], root2 = []
Output: [- 1010 01010]
Tip:
Each tree has a maximum of 5000 nodes.
The value of each node is between [- 10 ^ 5, 10 ^ 5].
3, the train of thought of solving the problem
Depth first search, array sort operation
4, problem solving procedure
Import java.util.ArrayList
Import java.util.Collections
Import java.util.List
Public class GetAllElementsTest3 {
Public static void main (String [] args) {
TreeNode T1 = new TreeNode (2)
TreeNode T12 = new TreeNode (1)
TreeNode T13 = new TreeNode (4)
TreeNode T2 = new TreeNode (1)
TreeNode T21 = new TreeNode (0)
TreeNode T22 = new TreeNode (3)
T1.left = T12
T1.right = T13
T2.left = T21
T2.right = T22
GetAllElements (T1, T2)
}
Public static List getAllElements (TreeNode root1, TreeNode root2) {
List list = new ArrayList ()
If (root1 = = null & & root2 = = null) {
Return list
}
List root1List = new ArrayList ()
List root2List = new ArrayList ()
DfsRoot1 (root1, root1List)
DfsRoot1 (root2, root2List)
Root1List.addAll (root2List)
Collections.sort (root1List)
Return root1List
}
Private static void dfsRoot1 (TreeNode root1, List root1List) {
If (root1 = = null) {
Return
}
If (root1.left! = null) {
DfsRoot1 (root1.left, root1List)
}
Root1List.add (root1.val)
If (root1.right! = null) {
DfsRoot1 (root1.right, root1List)
}
}
}
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