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Solution.java
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Solution.java
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package g0601_0700.s0653_two_sum_iv_input_is_a_bst;
// #Easy #Hash_Table #Depth_First_Search #Breadth_First_Search #Tree #Binary_Tree #Two_Pointers
// #Binary_Search_Tree #Data_Structure_I_Day_14_Tree
// #2022_03_21_Time_5_ms_(74.23%)_Space_52_MB_(27.36%)
import com_github_leetcode.TreeNode;
import java.util.ArrayList;
import java.util.List;
/*
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
public class Solution {
public boolean findTarget(TreeNode root, int k) {
if (root == null) {
return false;
}
List<Integer> res = new ArrayList<>();
inOrder(res, root);
int i = 0;
int j = res.size() - 1;
while (i < j) {
int val1 = res.get(i);
int val2 = res.get(j);
if (val1 + val2 == k) {
return true;
} else if (val1 + val2 < k) {
i++;
} else {
j--;
}
}
return false;
}
private void inOrder(List<Integer> res, TreeNode root) {
if (root == null) {
return;
}
inOrder(res, root.left);
res.add(root.val);
inOrder(res, root.right);
}
}